7th grade sci

Bases Although acids are a significant part of chemistry, other groups of compounds are equally important and interesting. If a small piece of sodium (Na) is placed in water, a spectacular reaction occurs. The sodium rushes about on the water surface and many bubbles are formed. A small explosion may occur, emitting yellow flames. The reaction continues until the sodium disappears. In water, the reaction occurs between the sodium and water creating sodium hydroxide, hydrogen gas and heat energy. The reaction is very energetic, causing the heat generated to ignite the hydrogen gas produced. The chemical reaction is written as: 2Na(s) + 2H2O(l) → 2NaOH(aq) + H2 (g) + heat energy. The sodium hydroxide (NaOH) resulting from this reaction is a base. In this section, you will learn the properties of several common bases. Here are your goals for this lesson: Describe properties common to all bases List some common bases Provide an example of an indicator for a base Vocabulary ammonia The gas NH3. methyl A hydrocarbon radical containing one positive charge (CH3). neutral Having no preference or tendency to move one way or the other; neither acid nor base. Vocab Arcade PROPERTIES OF BASES All bases have certain characteristics in common. They usually taste bitter and feel slippery. Bases dissolve fats and oils. All bases contain at least one metal plus hydrogen and oxygen combined in a hydroxide ion. Another name for base is alkali. Lye, ammonia, and milk of magnesia are common household bases. The most common base is sodium hydroxide. It is part of lye and is used in making soap. Lye is used to unclog sink drains because it dissolves oil, fat, and grease. Ammonia gas dissolved in water is used in cleaning compounds such as window cleaners. Milk of magnesia is most commonly used as a laxative. Figure 15 lists some common bases and their uses. THE HYDROXIDE ION If the gas given off in the reaction of sodium and water is tested, hydrogen is found. If sodium and water are allowed to react, the water evaporates and leaves behind a white substance. The white substance remaining is sodium hydroxide (NaOH). The formula for water, H2O, can be rewritten H(OH). Since water contains hydrogen ions (H+), (OH-) ions must also be present. These OH- ions are called hydroxide ions. This dissociation (breaking apart) reaction can be written: One water molecule makes one hydrogen ion plus one hydroxide ion. The number of these ions in water is very small, but is large enough that reactions between water and the active metals can occur. Sodium hydroxide is a base. Bases are characterized by the formation of OH- which results when the bases are dissolved in water. Bases that produce many OH- ions in water solution are strong bases. Those that produce few OH- are weak bases. Since it produces hydrogen and hydroxide ions, water has characteristics of both acids and bases. pH OF BASES The degree to which a substance is acidic or basic is often expressed in terms of its hydronium ion (H3O+) concentration. The hydronium ion concentration of a substance is represented by the symbol pH. When a hydrogen ion combines with a water molecule, the result is the hydronium ion H3O+. It is an ion because it has a positive charge. The hydronium ion can easily split into a molecule of water and a hydrogen ion. The pH scale ranges from 0 to 14: above 7 is basic and below 7 is acidic. Strong bases have a pH of 12 to 14. Weak bases have a pH of 7 to 12 on the scale. The concentration of hydronium and hydroxide ions in a solution varies inversely; that is, as hydronium ion concentration increases, the hydroxide ion concentration decreases. A low pH value means a high hydronium (H3O+) concentration. A high pH value indicates a high hydroxide ion concentration. Indicators. The use of an indicator is both an exact and a safe way to test for an acid or base. Indicators are substances that can turn different colors in solutions. Their colors depend upon whether the solution is acid or base. Litmus paper is one indicator that can be used to test for a base. You have already learned that blue litmus paper will turn red in an acidic solution. Red litmus paper will turn blue in a base solution. If neither type of litmus paper changes color, the solution is neutral. A neutral solution is neither an acid nor a base and is 7 on the pH scale. Other common indicators are methyl orange, methyl red, bromothymol blue, and phenolphthalein. Each indicator has a characteristic color change for acids and bases. For example, phenolphthalein is colorless in an acid solution and pink in a basic solution. Litmus paper and phenolphthalein are the most common indicators used in the laboratory. NOTE: Never put any foreign substance in your mouth or on your tongue. This practice could prove harmful to you.

Foods and Digestion Nutrients are the substances in foods that promote growth, repair body tissue, provide energy, and keep cells healthy and functioning properly. If your body does not get the correct amounts of all the nutrients it requires, certain parts will not function the way they should. Disease may begin and could remain unnoticed until it becomes serious. The body must process foods both mechanically and chemically in order to get usable substances from them. This process--digestion--and the body organs involved will be a part of what you learn in this section. Here are your goals for this lesson: List the six types of nutrients and provide examples of each Examine the purpose of each nutrient Trace the path food takes through the digestive system Vocabulary absorption The process of passing into the bloodstream or lymph system the materials of nutrition. amino acid Any of a group of essential substances containing nitrogen that form the building blocks of protein. cell Basic unit of living organisms. enzymes Proteins in the body which quicken chemical reactions. hormones Chemical substances formed in certain organs of the body; necessary for body growth and digestion. metabolism Chemical and physical process in the body which breaks down food, releases energy, and builds new cells. schematic A diagram or simplified drawing of something. soluble Able to be dissolved; able to go into solution. Vocab Arcade SIX KINDS OF NUTRIENTS Six basic types of nutrients are carbohydrates, fats, proteins, minerals, vitamins, and water. All foods will contain one or more of these nutrients. Carbohydrates. Carbohydrates are nutrients containing carbon, hydrogen, and oxygen. Carbohydrates are found in sugar and starchy foods such as bread, cake, candy, cereal, potatoes, and many other foods. In fact, this nutrient is the easiest one to get because so many foods contain carbohydrates. Why do we need this nutrient? We need it for energy. Carbohydrates quickly dissolve and enter the bloodstream, giving us quick energy. Fats. A fat is an oily animal or vegetable substance. Fats belong to a group of molecules called lipids. Lipids, like proteins and carbohydrates, contain carbon, hydrogen, oxygen, and nitrogen. Lipids include waxes, steroids, fats, and fat-soluble vitamins such as A, D, E, and K. Fats are another source of energy, but this nutrient is not used by the body as rapidly as are carbohydrates. Healthy skin requires "essential fatty acids." Vitamins A, D, E, and K are fat-soluble and must be carried by fat molecules in the bloodstream. Fats are stored throughout the body as fatty cells. We need very little actual oil or fat in our daily diet. Peanuts, meat, butter, milk, cheese, and salad dressing contain fat. Proteins. Proteins are molecules containing carbon, hydrogen, oxygen, and nitrogen. These proteins are essential to the diet of all people and animals. The building blocks of all proteins are amino acids. Twenty-one different kinds are essential. They are only found in foods containing protein. Without the necessary proteins, cells cannot reproduce or repair themselves. Proteins are also needed to help form antibodies, which fight infection, in the blood. Protein aids in the production of hormones and enzymes and provides energy when carbohydrates and fats are gone. Meat, fish, poultry, eggs, milk, cheese, dried beans, peas, whole-grain cereals, and many other foods contain protein. Not all protein is "complete" (contains all the essential amino acids). Therefore, we need many types of protein foods daily. Minerals. Minerals are substances that are neither animal nor vegetable. Minerals are found throughout the earth as naturally occurring elements or compounds in rocks and water. Minerals in foods are essential in the daily diet. These substances occur naturally in plants through absorption of dissolved minerals in water. Many minerals are essential to our good health. They combine with other nutrients to perform a variety of functions. A few of the most necessary are calcium, phosphorus, iron, and iodine. Calcium is found in milk, cheese, and dark green vegetables (including broccoli, kale, and turnip greens). Calcium is used in the body to form bones and teeth. It helps blood to clot and helps keep the heart beating. Calcium helps muscles and nerves work and helps regulate the use of other minerals. Phosphorus is found in the same foods that supply calcium. Phosphorus is also found in seafood, meats, eggs, cereals, and most vegetables. It is needed by bones, teeth, and nerve fibers. Phosphorus is needed by all cells in small amounts to help them use other nutrients for energy. Iron is found in liver; eggs; meat; green, leafy vegetables; beets; raisins; dried apricots; dried beans and peas; and whole-grain cereals. Iron is needed by all cells, but especially by red blood cells to help carry oxygen. Iodine is only found in seafoods, in plants grown in soil near the sea, and in iodized table salt. Iodine is absolutely necessary in the body to help control the rate of metabolism of food. Other minerals needed for your body to be healthy are small amounts of copper, magnesium, sulfur, and sodium. Vitamins. Vitamins are complex organic chemicals needed in relatively small amounts in the diet for normal growth and health. Unlike carbohydrates, fats, and proteins, vitamins do not supply energy. They are essential for the body to use energy and to regulate metabolism. Without vitamins, normal growth and health is not possible. The vitamins most important for good health and their uses in the body are shown here. TABLE 1 VITAMIN PRINCIPAL FUNCTION FOODS Vitamin A Helps keep skin healthy, mucous membranes firm and resistant to infection; protects against night blindness, promotes healthy eyes. Milk; butter; vegetables; egg yolk;cheese; liver The B Vitamins: B1Thiamin, B-2 Riboflavin, B-3 Niacin,B-6, B-9, Folic Acid, B-12 Major substances in the release of energy from food; helps the nervous system function properly, helps keep appetite and digestion normal, helps prevent anemia, helps enzyme and body chemistry to function normally. Meat; fish; poultry; eggs; dried peas;dried beans; milk; cheese; whole grains; green, leafy vegetables;peanuts Vitamin C: Ascorbic Acid Helps in forming blood cells, helps make walls of a blood vessel firm, helps resist infection, helps prevent fatigue, aids in healing, and prevents scurvy. Citrus fruits, most raw fruits and vegetables Vitamin D Helps the body absorb calcium from digestive tract, helps build calcium and phosphorus into bones. Milk fortified with Vitamin D; butter; fish liver oil; sunshine Vitamin E Helps cells to function normally. Vegetable oils; wheat germ; liver; whole grains; lettuce Vitamin K Helps blood to clot. Green vegetables Neanderthal Man and Vitamin D. This hunched over, club-carrying, brutish person is described as an evolutionary link between humans and ape. Scientists, called pathologists, have now carefully examined the Neanderthal remains. We are now certain from scientific investigations that the Neanderthal man is fully human, just like you. The bones of some Neanderthals had suffered from a disease called rickets. This disease causes abnormal bone growth and deformity due to a lack of Vitamin D. Vitamin D requires exposure to sunshine and a proper diet. It appears that Neanderthal man lived in Germany, just south of the great ice sheets which covered the Earth after Noah's flood. At that time, living conditions in the cold, humid climate and overcast skies contributed to arthritis and rickets. Neanderthal man has been shown to be fully human by scientists with knowledge of the value of nutrition. The exaggerated drawings of Neanderthal man carrying a club are not based on scientific facts. These drawings and museum mock-ups are the products of someone's imagination. Click here for more information about prehistoric humans. Water. Water is not always considered a nutrient, but you could live only a few days without it. Water is needed to carry nutrients to cells and to carry away their waste products. Your body is about 70 percent water. Each day you lose about six pints (3 liters) of water. Water evaporates from your lungs and skin constantly. This evaporation helps regulate your body temperature as food is oxidized (burned) for energy. However, you do not need to drink six pints (twelve cups) of water each day to replace your loss. Water is in every liquid you drink. Even solid food contains much water. Four to eight glasses of water, including milk and juices, is usually enough. DIGESTIVE SYSTEM If your stomach kept all the food you ate in a day and did not pass the food on, it would look like a basketball! Of course we know your stomach does not have whole hamburgers, whole apples, or neat-looking candy bars in it! You chew them up, right? Well, what then? You swallow, something happens, and in a few hours you feel like eating again. Through complex processes, both mechanical and chemical, food becomes usable by the body for energy, cell building, and maintenance of good health. These processes at first seem simple. We can even draw a schematic of the digestive system. However, when we consider the way our bodies are so completely interrelated, the marvel of God's creation is really exciting. Digestion. Digestion is the process of breaking down food into particles small enough to be dissolved in the plasma of the blood. The digested food is carried by the bloodstream to be absorbed by all the cells of the body. Also, part of digestion is changing food, through chemical processes, into other simpler substances that can then be used by the cells. Mouth. The first step in digestion takes place in the mouth. Saliva contains a digestive enzyme that begins the change of carbohydrates into sugar. Then the sugar can dissolve. The other kinds of nutrients taste good, and your teeth grind them up, but digestion of protein and fat has not begun. The esophagus is the tube leading from your mouth to your stomach. Your esophagus has ring-like muscles that squeeze the food and push it down into your stomach. Stomach. The stomach has thick walls of muscles that squeeze and churn the food into a thick, pasty lump. The stomach makes enzymes and other chemicals; and, as it churns, it continues the process of digestion. Your food, by now, is in a very liquid state. Saliva from your mouth and stomach and such chemicals as hydrochloric acid (HCl) and pepsin have begun to break down protein. Fats are not broken down until they reach the small intestine. Small intestine. After food is broken down and partially dissolved in the stomach, the stomach muscles push the food on into the small intestine. Two small organs, the gall bladder and the pancreas produce enzymes that enter the small intestine in small amounts and complete the digestion of your food. Your food is now completely liquid and contains amino acids from the proteins, digested fats called fatty acids and glycerin, and simple sugars--mostly glucose. Vitamins and minerals do not change. They are in the digested liquid and pass directly into the bloodstream. Large intestine. Even though the digested food is in liquid form, some particles of food will not dissolve into tiny enough particles to enter the bloodstream. Some particles are as small as molecules. The particles that have not been dissolved are waste products which pass into the large intestine. This waste then leaves the body. Plasma. Each cell in your body has to be nourished, and your bloodstream is the "vehicle" for carrying nutrients to those cells. The liquid part of the blood, plasma, is what carries the dissolved nutrients from digested food. As the heart pumps the blood throughout the entire body, red blood cells bring oxygen to all other cells and carry away carbon dioxide. This process goes on continuously. Nutrients and water pass into the bloodstream as it flows through blood vessels in the small intestine. At the same time, some blood collects oxygen from the lungs and gets rid of carbon dioxide. Waste products from cells are taken care of by the kidneys or pass out through the skin pores. Cells are nourished by nutrients for reproduction and repair.

Atoms and Molecules Since the days of ancient Greece, people have tried to explain the composition of matter. According to one theory, air was emptiness. Today we know that air is not emptiness. It is a mixture of gases that have mass and occupy space. Another theory stated that the four elements of the universe were air, earth, fire, and water and that each of these four elements had two of these four properties: heat, cold, moisture, or dryness. No one ever proved this idea, and modern scientists do not believe it. Today we know that the universe is made up of more than one hundred elements. Matter is composed of elements and molecules. Elements and molecules combine to form compounds. Compounds that occur naturally in the crust of the earth are called minerals. In this section, you will study atoms and how they form the basis of all matter. Just as we believe in God even though we do not see Him, we will study atoms even though we do not see them. Principles in both the spiritual realm and natural realm often work the same way. As you study atoms and molecules and how they link together, notice that science only goes so far in explaining things. As Christians, we know the ultimate force that holds things together and maintains natural order is God. Here are your goals for this lesson: Discuss the contributions made by Dalton, Bohr, and Chadwick to the development of the atomic theory List the three major types of atomic particles and their properties Define atomic mass (weight) Vocabulary atomic mass Approximately, the number of protons plus neutrons in an atom. atomic number The number of protons in an atom; a number unique to each element. charge A positive or negative electrical quality. compound A union of two or more different elements in definite proportion by mass. electron An atomic particle with a negative charge. element One of the over 100 kinds of atoms that make up matter; a substance made up of only one kind of atom. neutron An atomic particle that has no charge (neutral) and is found in the nucleus. nucleus The center of the atom. orbital The path in which an electron travels around the atom. proton An atomic particle which is positively charged and found in the nucleus. valence The combining power of an atom. Vocab Arcade ATOMS Suppose you divided an element into two pieces and continued to divide each piece into smaller and smaller pieces. At some point, you would not be able to divide the pieces and still have pieces of that same element left. The smallest piece of an element which still has the properties of that element is called an atom. All elements are composed of atoms. History of atoms. The idea of atoms has been around since ancient Greek civilization. Later, John Dalton (1766-1844), an English chemist proposed an atomic theory. Dalton believed that all matter was made up of small particles called atoms and that atoms could not be broken down any further. He was correct that all matter is made up of atoms, but he was incorrect in his belief that atoms could not be divided. In 1913, Niels Bohr (1885-1962), a Danish physicist, drew a simple picture of the atom. The atom, as Bohr imagined it, consists of a nucleus surrounded by electrons. The electrons whirl around the nucleus in orbital paths. The empty space between the nucleus and the electrons makes up most of the volume of an atom. Although changes have been made to the structure suggested by Bohr, the Bohr atom still serves as a model for atomic structure . James Chadwick, an English physicist, discovered the neutron in 1932. Meanwhile, various scientists contributed to finding the existence of the proton. Look at Figure 7 of the carbon atom. As the drawing shows, the carbon atom has six protons and six neutrons in its nucleus. Surrounding the nucleus in orbital paths are the electrons. The carbon atom has six electrons. Two electrons are in the innermost shell, and four electrons are in the outer shell of the atom. Diagrams like the carbon drawing are useful. Such models make it easy to see the specific structures of various atoms. However, it is important to recognize their limitations. The drawing suggests that an atom is flat. In reality, an atom is three-dimensional. In other words, it is more like a ball than a saucer. The drawing also suggests that electrons continuously travel the same flat path. Electrons whirl around the nucleus in a variety of paths and in a variety of directions. The electrons travel near the speed of light and are sometimes looked upon as energy waves instead of bits of matter. Electrons move so fast through the space around the nucleus that the space is often described as the electron cloud (Figure 8). The space seems filled, not because so many electrons are there, but because they move so fast. The "electron cloud" concept could be demonstrated by shaking a jar of marbles so fast that the marbles seem to be everywhere in the jar at every moment. All the space in the jar seems to be filled. Parts of the atom. Scientists once thought that an atom was a small, solid ball. We now know that it is actually made up of very small particles. The main particles are protons, neutrons, and electrons. The proton (p) is a particle that has a positive charge. It has a mass 1,800 times larger than an electron. The proton is found at the center of the atom inside the nucleus. A proton, shown by a positive sign (+), balances out the negative charge of an electron. The neutron (n) is also found in the nucleus. It has nearly the same mass as the proton. However, it is different from the proton in that it has no electric charge. It is neutral. Therefore, it is neither positive nor negative. The electron (e) is a particle that has a negative charge and is found outside the nucleus. It has very little mass. An electron is shown by a negative sign (-). Electrons revolve around the nucleus and are in constant rapid motion. Electrons which are at the same average distance from the nucleus occupy the same shell. These shells are sometimes given a letter to identify them. An atom can have up to seven electron shells. Chemists refer to these shells as n = 1, 2, 3, 4, 5, 6, and 7. Only in atoms with very high atomic numbers do we find n = 6 and n = 7. Each shell can have only a limited number of electrons. The first shell, n = 1, is called the inner shell. It can only have two electrons, while the second shell, n = 2, can have eight. The third shell, n = 3 can only have 18 electrons. The fourth shell, n = 4, can have 32, and so on. When a shell is filled, the remaining electrons fall into the next outer shell. Light atoms like hydrogen have fewer shells than heavy atoms like uranium. Electrons in the outermost shell are called valence electrons. An atom's valence tells to what extent an atom can combine or join with other atoms in a chemical reaction. Only the electrons in the outermost shell take part in these reactions. In the early 1960's, Murray Gell-Mann came up with the idea that within the protons and neutrons are even smaller particles, named quarks. Many scientists now believe that quarks may be the most basic unit of matter. Quarks have been found to have both a mass and an electrical charge. Recently, scientists have begun classifying quarks based on "color charge". There are seven different "color charges", red, green, blue, cyan, magenta, yellow, and white. Nearly all the mass of the atom is found in the nucleus, which is made up of protons and neutrons. Atomic mass is the sum of protons and neutrons. The number of protons in an atom is always equal to the number of electrons. Thus, the total charge of an atom is zero or neutral because the protons and electrons have equal but opposite charges. Since these opposite charges cancel each other, an atom has no electrical charge.

Molecules God's universe fits together. You have learned that one atom differs from another atom partly because the atoms contain different numbers of electrons. These electrons help atoms combine or bond with other atoms. In this section you will study how atoms combine to form larger particles called molecules. Here are your goals for this lesson: Define molecules Describe how bonds are formed in molecules Explain the molecular model of matter A molecule is the smallest unit into which a compound can be divided and still be that same compound. For example, every molecule of water is identical. Each molecule of water is made up of two atoms of hydrogen and one atom of oxygen. If you break down the water molecule, you no longer have water. A molecule is formed when two or more atoms combine (bond) chemically. A bond consists of two electrons shared between two atoms, making up an electron pair. The first figure below is a diagram of an oxygen molecule. Notice the circled electrons between the two oxygen atoms. The electron pair within the circle is made up of one electron from each of the oxygen atoms. This electron pair is then shared between the two atoms, forming a bond and connecting the atoms together. Since each atom "wants" the electron provided by the other atom to complete its outer shell, the atoms are held together. The electrons are shared and the molecule maintains a net zero charge with neither atom possessing the extra electron by itself. As a molecule undergoes a chemical reaction, the existing bonds are broken apart and new bonds form with electrons from different atoms making new electron pairs. Some molecules are made up of two or more atoms of the same element. The figure at right shows the oxygen molecule as an example of this combination. Two atoms of oxygen combine to form an oxygen molecule (O2). Notice that the number of electrons in each atom is the same as the number of protons. Oxygen has eight protons and, therefore, must have eight electrons to balance the charge (eight positive and eight negative). Two of the eight electrons are in the inner orbit (n = 1), and six are in the second orbit (n = 2). The two oxygen atoms share two pairs of electrons between them; therefore, each atom has eight electrons in its outer orbit. You will remember in the section on the atom that the second orbit (n = 2) can hold a maximum of eight electrons. That is why each of the oxygen atoms is able to have a total of eight in its outer orbit. The diagram also shows eight neutrons in the nucleus. Other molecules are made up of two or more atoms from different elements. The picture of carbon dioxide (CO2) below shows the atoms of carbon and oxygen combined to form the molecule. Each oxygen atom has six electrons in its outer orbit, and the carbon atom has four electrons. By sharing electrons, each of the atoms has a filled outer orbit (n = 2) of eight electrons. Also notice that all three atoms have the maximum two electrons in the inner (n = 1) orbit. Some molecules are very complex and have hundreds of atoms sharing electrons. The molecular model helps explain matter existing in the form of solid, liquid, or gas. In a solid, the molecules are closely packed together. They do not have room to move away from each other. This close packing maintains a solid's definite, constant shape. In a liquid the molecules shake back and forth. This shaking is called vibration. The molecules are in constant motion as they slip and slide over each other due to weak bonding. As a result, a liquid does not have a definite shape. How are the molecules arranged in a gas? In a gas they are much farther apart than in either liquids or solids. The molecules move rapidly in straight lines until they hit other molecules and bounce off. They will continue to spread out unless they are contained. That is why a gas has neither a definite shape nor volume.

Salts You will recall that salts are formed by combining an acid with a base. A salt is neither an acid nor a base. One substance acts to counteract the other. As acids and bases combine to form salts, these newly formed substances possess an entirely different set of properties. In this lesson, we will explore this in greater detail. Here are your goals for this lesson: Describe a salt and provide examples Explain a neutralization reaction Explain what an electrolyte is Vocabulary mineral Any element or compound which occurs in the rocks of the earth. neutralize To make of no effect by some opposite force. property A quality belonging to something. Vocab Arcade NEUTRALIZATION Acids and bases react with each other in a chemical reaction called neutralization. In neutralization, the properties of both the acid and the base are destroyed. Neutral means that a substance is neither acid nor base. This concept explains why weak bases are used to counteract acids spilled on clothing. Baking soda is a common base used to neutralize acids. Antacids containing bicarbonate of soda are used to reduce indigestion resulting from excess stomach acid. In neutralization, hydronium ions (H3O+) of the acid unite with hydroxide ions (OH-) of the base to form water (H2O). The neutralization reaction can be written: This process also reduces the number of free, or excess, ions still available in the solution. If the water is evaporated after a neutralization reaction, a solid substance called a salt remains. A salt is formed from the positive ion of the base and the negative ion from the acid. For example, when sodium hydroxide (NaOH) is neutralized by hydrochloric acid (HCl), sodium chloride (NaCl) is formed. Sodium chloride is ordinary table salt. The following equation summarizes this reaction: When the base (sodium hydroxide) and the acid (hydrochloric acid) are mixed in correct quantities, a salt (sodium chloride) is formed. USES OF SALTS Water often contains calcium and magnesium mineral salts. When a significant amount of these minerals is dissolved in water, the water is said to be hard. Hard water is not ideal for washing and bathing because it requires more detergent and leaves hard water film in clothes and on appliances. Hard water occurs naturally in many parts of the world where undergroundwater seeps through rocks containing calcium and magnesium minerals. Soft water has a very low mineral content and is ideal for cooking, washing, and bathing. Many homeowners have commercial water softeners that use salt to remove minerals and reduce the "hardness" of their household water. Figure 18 shows several salts and their uses in everyday living. ELECTROLYTES Acids, bases, and salts are examples of compounds called electrolytes. Electrolytes are substances that conduct electricity in water solutions. They conduct electricity because they break into ions in water. An ion is an atom that has unequal numbers of electrons and protons. This unequal number of charged particles gives the ion a charge. For example, the sodium ion, with one more proton than electrons, has a positive charge. The chlorine atom, by gaining an electron, becomes a chloride ion with a negative charge. Electrolytes that supply many ions to a solution are called strong electrolytes. Electrolytes that supply few ions to a solution are called weak electrolytes. Electrolytes are able to conduct electricity because the charged particles (ions) move through the solution when voltage is applied. When the voltage is applied to the solution through the electrodes as shown, the positive and/or negative ions present will move toward the electrode of opposite charge. The movement of charged particles through a solution produces an electric current.

Nutritional Diseases All the plants and animals were created perfect for our use. The soil was rich and full of nutrients necessary for plant growth. The soil and fresh water at that time were to be the source of nutrients for all living things. In this section, you will be presented with some facts about nutrition today, nutritional diseases and deficiencies, allergies, and additives. Here are your goals for this lesson: Discuss the use of chemicals in food production and their effects Examine the importance of healthy foods to a diet Describe symptoms of various vitamin deficiencies Evaluate the relationship between allergic reactions and addiction reactions Vocabulary deficiency A shortage of something essential. pesticide A man-made chemical developed to protect crops from insects. preservative An added substance used to slow down or stop spoiling. susceptible Able to catch a disease because of a condition or weakness. supplement Add to, help; an aid or an addition. Vocab Arcade NUTRITION: WHAT IS AND WHAT SHOULD BE As the Lord blessed the United States with prosperity, the invention of new industrial machines, modern transportation, and the discovery of new chemical processes and synthetic materials, the desires and wants of the people grew. The average citizen was able to have many things that a few years before would have seemed almost a miracle. The emphasis began to focus on more production and newer, fancier things. Food products were no exception in this new direction. The food processing practices that are currently common were developed several decades ago. Canning, however, has been with us for many more years than that. Dry packaging is cheaper for the food processor, so new techniques were developed to preserve foods for transporting. In order to fill the markets to serve the growing cities, techniques for longer food storage had to be developed. To raise more insect-free crops, farmers began to use pesticides. The earth had to be fertilized to put back nutrients that the crops used. Scientists produced new chemicals to use as fertilizer--natural animal waste was awkward and unpleasant to use. At the same time, refineries and manufacturing plants were polluting skies and rivers. Some of the farmlands were infiltrated with toxic waste through contamination of groundwater. In an effort to get more food and conveniences, people have not always been concerned about the future. As a result, the pesticides, fertilizers, and preservatives have built up over time and have poisoned much of the land, water, and food. Scientists now are trying to control the use of chemicals in food production and storage. Some preservatives, dyes for coloring, and other additives are no longer being used. Another food problem affecting many parts of the world is the overuse of "junk food." This term describes foods that are especially high in sugar and/or fat and poor in nutrition. "Junk food" can be found in abundance in all modern supermarkets and many restaurants. "Junk foods" are those foods that have been highly processed and refined. In this refining process, most, if not all of the nutritional value has been lost or destroyed. Many people eat mostly "junk foods" every day. Some of you who are working in this unit may obtain your food directly from a farm, perhaps your own. You may live in a community where produce or livestock is raised for the market. You are familiar, then, with local practices. There are several highly successful farms that are not using chemicals in any form. They are using present knowledge and are guided by the conviction that humans must be a better steward of the earth, as the Lord intended. Things we eat, pollutants in the air we breathe, and things that are put on the skin are all absorbed into the body. The circulatory system, through the bloodstream, kidneys, spleen, and other body-defense mechanisms, attempts to rid the body of toxins. Many toxins can cause damage to cells, tissue, and various organs before they can be disposed of by the body. God created everything good and pure for us. We should attempt to eat and live as He intended. Look for additive-free foods; select those meats and produce that have not been chemically treated. Buy unrefined cereal and flour products. Click here for more information on good food choices for your age group. ChooseMyPlate NUTRITIONAL DEFICIENCIES A well-recognized group of diseases is known as "deficiency diseases." These diseases are abnormal diseases because they are caused by the absence of specific substances usually found in a normal diet. Due to climate, geography, finances, and food processing, many people throughout the world suffer from nutritional disease. Diseases that are recognized today as being caused by vitamin deficiency have probably been in existence several hundred years. To produce an obvious "disease," there must be an extreme lack of a vitamin or mineral. Even though you may be getting enough vitamins or minerals to feel "okay," you may not be getting enough to betruly healthy. Generally, all "deficiency states" (conditions) lead to tiredness, weakness, gain or loss of weight, and emotional changes. Often, when deficiency is just beginning to become noticed, it is difficult to tell which vitamin or mineral is lacking. Most people in the United States are not in danger of dietary disease but are in danger of deficiency conditions or states. Vitamin A deficiency. Vitamin A keeps eyes, skin, and hair healthy. It is essential for growth and, because many infections enter the body through the skin, it helps prevent infection. The most obvious symptom of Vitamin A deficiency is dryness of the eyes. Severe lack of Vitamin A can lead to these conditions: (a) severe, and sometimes fatal, infections in children; (b) tissues covering the digestive tract, urinary tract, or respiratory tract becoming dry, hard, thicker, and susceptible to infection; (c) partial or complete blindness (a frequent cause of blindness in the Orient)--night blindness is often a first symptom; and (d) dry, scaly, shriveled, and possibly pigmented (dark blotches) skin. Vitamin A is found in fatty foods of animal origin, such as milk, butter, cod-liver oil, and egg yolk. Vitamin A is a yellow substance called carotene. Carotene gives color to green or yellow vegetables, such as carrots, sweet potatoes, yellow corn, and green beans. Carotene can be extracted in the laboratory. It is very potent and is converted in the body into what we know as Vitamin A. A Vitamin A deficiency can be treated simply by adding it to the diet. Vitamin B complex. The Vitamin B complex is made up of all the different B vitamins. All the members of this complex group of vitamins are closely associated in nature, and a deficiency in one can bring about a deficiency in others. Below you will find a list of the vitamins that belong to the Vitamin B complex. Vitamin B1 (thiamine) Vitamin B2 (riboflavin) Vitamin B3 (niacin) Vitamin B5 (pantothenic acid) Vitamin B6 (pyridoxine) Vitamin B7 (biotin) Vitamin B9 (folic acid) Vitamin B12 (cobalamins; commonly cyanocobalamin in vitamin supplements) Vitamin B¹ deficiency. Plants contain abundant Vitamin B¹ or thiamine. B¹ is found in yeast, rice bran, whole-grain flour, meat, dried beans, and peas. Scientists now recognize that the normal American diet is deficient in B¹ as a result of eating highly refined grains. People fed diets lacking Vitamin B¹ for several months begin suffering from fatigue, depression, irritability, low blood pressure, and loss of appetite. Beriberi is a disease that results from a Vitamin B¹ deficiency. Its symptoms include swelling of the limbs, weak heart, painful legs, and finally paralysis of the nerves. Vitamin B³ (niacin) deficiency. Niacin is found in liver, lean meats, and whole-grain cereals. Symptoms of pellagra (deficiency of niacin and other B vitamins) are these: (a) inflaming of the mouth with redness and soreness of the tongue; (b) cracking of the skin and sores around the mouth; (c) reddening and thickening of the skin on the back of the hands and forearms; (d) diarrhea, vomiting, and loss of appetite; and (e) other symptoms including headache, irritability, anxiety, and muscular weakness. Vitamin B² (riboflavin) deficiency. Severe deficiency of riboflavin results in breaks and cracks occurring in the corners of the mouth. Lips become red and a fine, dandruff-like scale appears at the openings of the nostrils, on the side of the nose, in the ears, and on the cheeks and forehead. The tongue becomes magenta-colored, the eyes are red, and bright lights cause the eyes to water and burn. These symptoms disappear within a few days when riboflavin (found in whole grains and green vegetables) is added to the diet. Vitamin C deficiency. Scurvy is a disease whose symptoms are serious weakening, excessive bruising, bleeding into the tissues, and bone softening. The occurrence of well-developed scurvy among adults is rare. It is seen sometimes in children who eat primarily starches and sweets. Vitamin C increases resistance to infection. In fact, dental caries (areas of tooth decay) are considered to be the possible result of Vitamin C deficiency. Vitamin C is found in oranges, lemons, limes, germinating seeds, fresh fruits, tomatoes, and vegetables. Vitamin D deficiency. Rickets is a disease of the bones. The bones are not normally hardened; therefore, a bending and twisting of the bones occurs during rapid growth. Certain foods, such as cod-liver oil, egg yolk, and foods treated with ultraviolet light (irradiated), contain Vitamin D which is used to treat rickets. Click here for more information about rickets Sunlight plays an important role in the hardening of bones. Ultraviolet rays cause the body to produce Vitamin D. Direct sunlight is not necessary because reflected light from the sky, clouds, buildings, and so forth possesses about two-thirds the effect of direct sunshine. Regular window glass does not allow ultraviolet rays to pass through, so indoor sun is not an adequate treatment of rickets. Winter months, when children are bundled up against the cold, do not provide enough ultraviolet light to prevent rickets. Therefore, adequate diet is necessary. ALLERGIES AND OTHER REACTIONS An allergy is a sensitivity to a substance which causes a reaction. Medical science has known for many years about obvious allergic reactions to certain foods. You may have heard about the person who breaks out from eating strawberries, someone who swells up from eating shellfish, or an individual who has an asthma attack after eating peanuts. More recent research is showing that many allergic reactions are addiction reactions. Reaction to a specific food may affect one or more organs or tissues. Each time a reaction occurs, it tends to affect the same system. Allergies can cause mental symptoms. The brain can show areas of allergic reaction similar to hives on the skin. There will be changes in circulation, and the increased pressure of this allergic reaction may cause swelling to be very severe. The most common reactions are headaches, fatigue (sleepiness at the wrong times), inability to concentrate, memory lapse, loss of coordination, and changes in perception from any of the five senses. These symptoms can be exactly like those symptoms that have been called neurosis or psychosis. All chemical additives found in food today can produce allergic reactions. Many people with long histories of strange behavior, nervous disorders, and hyperactivity are only showing results of the chemical sensitivity of the brain. Modern chemistry has contributed, both positively and negatively, to the behavior and health problems of Americans. Food addictions have become a popular area of research. Addiction happens slowly as a person eats or drinks frequently. If you are addicted to something, you feel better when you ingest it, after a period of being without it, you begin to feel worse. These withdrawal symptoms lead to addiction. Knowledge of addiction to high calorie, low-nutrient foods has now become a subject of intense scientific research and certainly should be considered as a possible cause of irritability, hyperactivity, inability to concentrate, fatigue, and other symptoms. Research on nutrition, additives, vitamins, and disease is on-going and is becoming one of the most important areas of scientific study today. One researcher stated that perhaps 90 percent of the population is suffering from some bodily metabolic imbalance. Unfortunately, many regular books and publications do not present recent research on nutrition and are still making such statements as "sugar is good energy" and "ice cream is a good substitute for milk." These statements are not true, and as a good steward of the temple of God, you need to be aware that much research is available for you to read for yourself. Because of the difficulty in getting adequate nutrients, vitamin and mineral supplements may be necessary. There is disagreement on whether synthetic (man-made) vitamins are as good for you as natural vitamins. Research shows that about half of the synthetic vitamins taken in cannot be used by the body. Natural vitamins contain all of the complex substances present in the original food substance, the way the Lord made them available for you.

Science Today In today's world, we are aware of new discoveries and inventions in every area of life. A cure for a disease, a pollution-control device for cars, a new type of toy--all point to fields of science and technology. We owe most of the comforts, conveniences, and pastimes of modern living to these fields. Today's science is based on the work of great people in the past. Those people did not stand by and allow others to accomplish their tasks. They had ideas, and they put those ideas into action. In this section we will learn what science is and what we owe to the scientists of yesterday. Here are your goals for this lesson: Define the term "science" Describe briefly the history of ancient and medieval scientists List the three renaissance scientists and their contributions Vocabulary alchemy The attempt to change base metals into gold by a mixture of science and magic. atom A building block of all matter. base metals Metals less valuable than gold. philosopher A person who attempts to explain some aspect of humans and the universe solely from natural logic or reasoning. Renaissance The rebirth of true learning. scholastics Medieval people who catalogued the ideas of ancient philosophers. science Orderly knowledge demonstrated by repeatable tests. summa An encyclopedia-like document written by a scholastic. Vocab Arcade A DEFINITION OF SCIENCE Let us develop a definition for the word science. Knowledge. The word science comes from a Greek word meaning knowledge. It is not enough, however, to state that science is knowledge, for many other areas could be included under this definition. If we add orderly to the word knowledge, we have narrowed our definition of science somewhat. Science is orderly knowledge. The statement "Ducks can swim, bears sleep in winter, and skunks smell," is correct; these facts are knowledge. The statement, "Different animals have certain characteristics that distinguish them from other animals: for example, ducks can swim, bears sleep in winter, and skunks have an unpleasant odor," is a more orderly way of presenting the same facts. It is more scientific. Experimentation. Science is more than orderly knowledge. Orderly knowledge can be found in fields other than science. The one area in which science differs from other fields of knowledge is experimentation. Experimentation is "demonstrating a fact by testing to see if the same result occurs repeatedly." For example, everyone knows ducks can swim; while some people know that swimming is a characteristic that makes ducks different from most other birds. A scientist, however, would attempt to prove this fact by placing several ducks in a pool of water to see if they could swim. He or she would be doing a test or experiment to prove that ducks can indeed swim. He or she would also be able to repeat the experiment with other ducks to show the same result. Thus, science is "orderly knowledge demonstrated by repeatable experiments." Doing an experiment to prove something as well-known as the fact that ducks can swim may seem ridiculous, but it is not. Without people who were willing to look ridiculous by doing experiments to prove ideas true or false, we might still believe some very false ideas. We will learn about some of these people in the next section. A BRIEF HISTORY OF SCIENCE When we think of science, we usually think of it as it is today: clean white labs, computers, serious people watching video monitors, and huge telescopes pointing to the stars. Science, however, is not a new subject. People have been seeking to understand God's creation ever since the Creation. Ancient science. Science began soon after people were created. However, science as an orderly system of thought did not begin until a Greek named Aristotle (Figure 2) began to record his ideas. Aristotle was a philosopher who wrote his ideas in an orderly manner. He studied nature and, among other things, tried to figure out a systematic classification for plants and animals. Though his ideas were orderly in their presentation, Aristotle is not considered a true scientist. He had ideas, but he never investigated to see if they were true. He never performed experiments. Because of this lack of experimentation, many of his ideas were faulty. Still, Aristotle's writings still are of value because they have inspired many later scientists. Another important Greek philosopher was Democritus. He was one of the first people to believe that all things consist of tiny particles of matter. He thought cutting a piece of matter in half again and again would ultimately result in a piece so small that it could not be halved. He termed this smallest piece of matter an atom which means not able to be cut. Atoms are quite small, but we now know that they are made of particles even smaller. Although Democritus' concept was not entirely correct, all of our atomic science is indebted to his idea. Medieval science. In the Middle Ages, which followed the barbarian invasions of the Roman Empire, science continued to exist, but not as we know it today. The most common form of science in the Middle Ages was alchemy. Alchemists were people interested in gaining great wealth. They thought it was possible to turn less valuable metals (base metals)--such as tin, copper, and lead--into gold. Of course, we know this process is not possible; but they did follow a somewhat scientific method. They did some reasonable things such as heating metals and pouring acids on them. Other procedures they used were less scientific. They relied upon magic to do what science seemed unable to accomplish. Of course, the alchemists never succeeded, but they did keep alive the idea of scientific investigation. Others who affected science during this period in history were the Arabs and the scholastics. The Arab Moors tried to invade Europe through Spain. They wished to spread Islam, the Muslim religion, throughout the world. The Moors brought with them advanced ideas in medicine and other scientific fields. Had they succeeded in conquering Europe, Christianity would have suffered, but Western science might have advanced much more rapidly than it did. Toward the end of the Middle Ages, people became interested in sorting out facts and writing them down in an orderly way. The scholastics had few new ideas, but they had rediscovered the writings of Aristotle and other ancient philosophers and created long works on their ancient writings. These works were called summas, or summaries, and they resembled encyclopedias. From this scholastic movement came the people who began the rebirth of science, art, and study of the Bible. This rebirth is called the Renaissance. RENAISSANCE SCIENCE This period of history saw a reawakening of true learning and original thought. The scholastics of the later Middle Ages borrowed most of their ideas from ancient philosophers. On the other hand, the people of the Renaissance produced new ideas and inventions. One of the most important pronouncements of the Renaissance was made by Nicolaus Copernicus (Figure 3). Copernicus was a Polish mathematician and astronomer. He stated the theory that the earth is not the center of the universe as the Roman Catholic Church had taught for centuries. However, he believed that the sun was the center around which the planets revolved. He also maintained that the earth rotated on its axis. The heliocentric theory was contrary to the prevailing idea that the earth was absolutely immobile. Copernicus was loyal to the Roman Catholic Church and so refrained from pushing his revolutionary ideas. His successor, however, was not so quiet. Galileo Galilei was also an astronomer. He studied the heavens through the telescope he made and came to the conclusion that Copernicus was correct in his theory. Galileo published a paper stating his findings. The Roman Catholic Church forced him to take back what he said. Even though he recanted, he was imprisoned and was watched closely for the rest of his life. Despite the fact that he was forced to recant his position, he never stopped believing it. Galileo gave the world a valuable tool with which to work: the knowledge that the planets revolve around the sun and that the earth turns on its axis. One of the greatest scientists of the Renaissance was Sir Isaac Newton (1642- 1727). Many scholars have judged him to be the greatest scientist who ever lived. Newton discovered three laws of motion and the Law of Universal Gravitation, which states that every object attracts every other object. These laws permitted scientists to mathematically calculate the position, speed, and paths of motion for all moving objects. He also developed the mathematics of calculus, which all physical scientists use routinely. Newton also invented the first reflecting telescope. The largest telescopes in the world are based on this technology. Sir Isaac Newton (Figure 4) believed in Jesus Christ as his Savior. He wrote many books concerning the Bible and defended the Bible's account of Creation. These people and many others contributed many scientific facts upon which modern science is built. The Renaissance merges gradually with modern times. Numerous scientists cannot be classified as strictly Renaissance, nor are they truly modern. We will study some of these scientists in the next section.

Post-Renaissance Science Great numbers of new discoveries were made during the Renaissance. Building on these discoveries, the people of the post-Renaissance period formulated theories in various fields. John Dalton (1766-1844) is recognized as the father of modern atomic theory. Dalton was a pious, Bible-believing Christian known as a Quaker. He helped to revolutionize the study of chemistry and formulated the practical gas law of partial pressures. His work started intense investigation into the understanding of atomic energy. Here are your goals for this lesson: Evaluate the evolutionary theory as purposed by de LaMarck and Darwin and the implications it had on scientific research Recognize the contributions of John Dalton and Louis Pasteur Name some modern scientists and their contributions Vocabulary electron A negatively charged atomic particle. evolution The theory that all organisms develop from simpler organisms. neutron A neutral atomic particle. organism An individual animal or plant. poliomyelitis A crippling disease, commonly known as polio. proton A positive atomic particle. species A group of animals or plants that have characteristics in common and are able to interbreed. Vocab Arcade The field of the biological sciences had many representatives. Scientists were curious about how traits or characteristics are passed from parents to their offspring. They were also curious about how the various types of plants and animals came to be the way they are. These ideas were common at this time because people were questioning the Bible as absolute truth. Some even denied the existence of God, at least as Creator and Controller of the universe. Since they did not accept God's Word, they believed they had to develop a new explanation for the origin of plants and animals. Jean Baptiste de LaMarck (1744-1829) was a French biologist. His theory was accepted as fact for many years and still is thought to be true by some people. He stated that some characteristics which organisms acquire after they are born can be passed on to their offspring. The example LaMarck's theory puts forth is the giraffe. In theory, the giraffe once had a short neck, but the need to reach higher branches caused its neck to become longer. Each generation of giraffes had longer necks than the generation before, resulting in the modern giraffes which have very long necks. In fact, the "need" for a longer neck will not induce the body to grow a longer neck. In addition, if the giraffe's neck could be stretched somewhat by continuous efforts to reach higher, this physical development, like a weight lifter building muscles, cannot be inherited by an offspring. Scientists have proven LaMarck's theory false repeatedly, but some people still insist on believing such statements as these: "The snake didn't use its long legs, so it gradually lost them." "I know my little boy has a weak right arm because I broke mine playing baseball when I was fifteen." These statements are not based on fact. However, due to ignorance, a large number of people hold that they are true. Another scientist interested in inheritance was Charles Darwin. He formulated the theory of evolution which states that all present-day species (types) of plants and animals developed over a long period of time from a few simpler ancestors. In the past 120 years, Darwin's theory has been generally adopted by the scientific community even though it has never been demonstrated by the scientific method of experimentation. It is now the basis of most other sciences, including biology. Evolutionists now say that all creatures began as microscopic organisms. Darwin's theory, along with its additions, has had a serious impact on the world, causing scientific research to be conducted in the wrong direction for more than a century. Many Christians have even accepted his theory. Yet the Bible can never agree with the theory of evolution. First, the Bible teaches an entirely different beginning of life--Creation. Typically, the work of James Ussher (1581-1656), was held to be true. Bishop Ussher's work set the time frame of Creation as 6,000 years ago. The theory of evolution would not allow this, since evolution as a process requires such a long period of time. Second, if humans gradually evolved from some lower form of life, there was no Garden of Eden, no temptation, and no Fall. Thus, there is no sin nature in each individual, and Jesus Christ died for no reason. For these reasons, the theory of evolution is no more than that--a theory, which attempts to explain creation without a Creator. A good representative of the period just preceding modern science of the twentieth century is Louis Pasteur (1822-1895). Pasteur, a Christian scientist, studied the action of microscopic organisms such as bacteria, and demonstrated that they can cause disease. He developed a process of pasteurization by which harmful organisms in certain foods (milk, for example) can be killed. Louis Pasteur also devised an experiment which demolished the medieval evolutionary idea of spontaneous generation. Spontaneous generation was an unfounded belief that life came into existence from decaying organic matter. The treatment of diseases based on this false notion had impeded the progress of medical science. Pasteur developed vaccines to combat several dreaded diseases such as rabies, diphtheria, and anthrax. His breakthroughs in medical science and biology have probably saved more human lives than any other person's. It took many years, but his persistence and sound experiments convinced many medical scientists to give up the idea of the naturalistic (evolutionary) origin of life. The people we have mentioned are only a few of those scientists who gave us useful ideas without which the scientific world of today could not function. As you continue to study science, you will notice that numerous scientific disciplines were founded by Christian scientists. These scientists started their investigations by believing what the Bible says about the origin of life and the universe. Because the Scriptures have never been shown to be false, a scientist will have a "head start" when probing the mysteries of the universe if his or her hypotheses are based on Scripture. Modern science. In the twentieth century both science and invention have progressed at a fantastic rate. Within the lifetime of one individual, the world has moved from the horse and buggy to supersonic jets and space stations. So many people have contributed to this expansion that it is difficult to choose those who are representative of them all. Just before the turn of the century, a woman scientist named Marie Curie made a discovery which has had results beyond anything she could have imagined. She left some unexposed film in a dark drawer with a piece of pitchblende. From pitchblende, she and her husband Pierre were able to isolate two elements that were not known before. These elements are radium and polonium, which give off what we now call radiation. For her work in this field, she and her husband shared the 1903 Nobel Peace Prize in Physics. One of the most famous people of the twentieth century was Albert Einstein, who was both a mathematician and a scientist. He discovered the relationship between energy and matter, expressed in the well-known equation E = mc2. This equation is read energy equals mass times the square of the speed of light. It means that if a small amount of matter is totally converted in a nuclear reaction, a tremendous amount of energy will be released. This theory has given rise to nuclear weapons as well as to the hope for useful energy from atoms. While Einstein was forming his ideas, another scientist, Niels Bohr, was developing a theory of atomic structure. He said that the atom has a dense center containing positively charged protons and neutral neutrons. Around this center, he believed, are orbits of varying sizes along which negatively charged electrons travel. Since Bohr's time, his atomic model has been subjected to many revisions, but he was surprisingly close to what seems to be the actual structure of the atom. Learn more about Albert Einstein. In the field of medicine, one of the most significant researchers was Dr. Jonas Salk. He and his staff developed a vaccine which prevents poliomyelitis, or polio. Because of his work, many people who might have been crippled or might have died have been spared this terrible disease.

Science and Technology Pure science is fascinating by itself, but it has also led to many exciting discoveries and inventions which are of practical use. The field of technology takes us into the area of science to which most people can respond more readily. Technology touches the everyday lives of most people on this planet. This lesson deals with the subject of technology. It will show how technology has progressed from simple machines to complex rocket guidance systems. And, in order to increase your understanding of the world in which you live, it will discuss certain problems caused by modern technology. Here are your goals for this lesson: Distinguish technology from pure science Provide examples of technology during ancient, medieval, renaissance, post-renaissance and modern times Recognize the importance of the invention of the printing press to the reading of Scripture Vocabulary animalcules The name given by Leeuwenhoek to the microorganisms he viewed through his microscope. cotton gin Machine that separates seeds, hulls and foreign materials from cotton in quantity. dynamo Large generator. engineer Scientist engaged in applying scientific principles to the invention or manufacture of machines. expansion Enlargement of material when heated. generator Device for producing electricity. gunpowder An explosive substance used in gunnery and blasting. inclined plane A man-made hill or ramp. industry The manufacture of goods. Industrial Revolution The change from an agricultural to industrial society in England (1750 - 1850). microscope A device for viewing things which are invisible to the unaided human eye. shaduf A device used by the ancient Egyptians to fill their irrigation ditches from the Nile River. stress A measure of pressure exerted on material. technology Application of science to practical uses. tensile strength The measure of stress at the moment of tearing apart. water mill A device that uses running water to grind grain. Vocab Arcade A DEFINITION OF TECHNOLOGY Pure science is interesting and valuable because it extends our understanding of God's creation. However, science needs to be applied before it is useful to human beings. Technology is applied science that makes pure science useful and practical. Technology has given rise to industry. Industry manufactures items which are useful to people. Each item uses one or many of the principles discovered by scientists and developed by professional engineers. Even a simple item such as a hand-held can opener applies the principles of the wedge, the wheel, and the lever. A complex machine such as a rocket or an automobile uses an amazing number of scientific principles. Most comforts and conveniences we have today are the result of technology. We could not have these things were it not for technologists who take scientific principles and apply them in original ways. For example, if a civil engineer wishes to build a sturdy and reliable bridge, he or she must know how to apply certain principles: 1. tensile strength -- how much stress materials (steel, concrete, etc.) can withstand without breaking when being pulled apart 2. expansion -- how much larger materials will get in hot weather 3. stress -- how much compression and tension materials can withstand Technologists also apply pure science to solving problems of society. One problem which is yet to be completely solved is that of a dwindling energy supply. Technologists are continually applying scientific principles in the search for new ways to produce and use energy sources. Technology applies the principles of pure science to the production of practical items. ADVANCES IN TECHNOLOGY Because technology is so much a part of our lives, we tend to think of it as something new and different. However, it is not new. It is as old as the history of humans. One of the first examples of technology in the Bible is the construction of the ark by Noah. Ancient technology. Early humans had the ability to use scientific principles. Scientists who study ancient humans (archaeologists) have uncovered evidence that their inventions and design of structures required remarkable understanding of scientific principles and mathematics. In fact, many discoveries have shown that ancient people developed some technologies in the fields of metallurgy, architecture, and astronomy which modern humans were not able to duplicate until the Renaissance. The invention of the wheel has enabled technologists throughout history to produce many other conveniences. Few complex machines could exist without the wheel. The farmers in ancient Egypt had a problem -- their land bordered the desert. The only protection they had against the desert was the great Nile River. They needed to get water to their farmland in the most effective way possible. To accomplish this feat, the Egyptians invented the shaduf, which used the principle of the lever. Water was stored in a raised cistern, and a bucket hanging from the end of a long pole was allowed to dip into it. Weights were added to the other end of the pole, serving to bring the bucket up and over the side of the cistern. The water was poured from the bucket into irrigation ditches and watered the land. Another invention of the Egyptians was the ramp, which is an inclined plane. An inclined plane does part of the work of lifting a heavy object. To build the pyramids, the Egyptians may have used long inclined planes. The longer the inclined plane the easier the load is to lift. It is still uncertain exactly how the Egyptians were able to lift huge blocks of stone into place to form the pyramids. Regardless, they accomplished these marvelous projects with a great deal of intelligence. Ancient technology produced many other useful items. Records of their technological knowledge were lost when the great library in Alexandria, Egypt, burned and when the Roman Empire was overrun by the barbarians. Many things have been rediscovered, but some are lost forever. Medieval technology. As the Western world recovered from the barbarian attacks and destruction, people began to invent different items to ease their lives. Since one of their first concerns was protection, they invented a variety of weapons. One of the most effective weapons was the crossbow. Unlike a regular bow and arrow, the crossbow was held horizontally; and, instead of an arrow, it shot a bolt. A bolt is similar to an arrow in that it is long; however, it is blunt, not pointed. The crossbow was a powerful weapon. The normal bow can be pulled only as hard as a persons arm can pull. The crossbow, however, uses a reel to pull back the bowstring. The reel is an application of two simple machines--the wheel and the lever. The idea is similar to reeling in a fish. You can pull the fish straight in by pulling directly on the line, or you can turn the handle of a reel and wind the string around and around. Using the reel, a person fishing has extra pulling power. As well, using the reel of the crossbow gave the archer more power to pull on the string. The more power behind the bolt, the farther and faster it could travel. People in the Middle Ages needed a more plentiful food supply. As population increased, more effective methods of food production were necessary. The invention of the water mill was one of the most important advances of that day. Water turned great wheels which turned grindstones. Large quantities of grain could be ground rapidly, and more people could be fed. In addition, water mills were used to turn saws to make more lumber available. Inventions advanced civilization in the Middle Ages by making life easier. With many of life's harder tasks completed by inventions, people could turn their minds to higher thoughts. It is safe to say that without the inventions of the Middle Ages, the Renaissance might never have been possible. One of the differences between humans and lower creatures is our ability to discover and invent. God has given humans a mind and the power to use it to unravel the mysteries of His creation. We have a responsibility to use the minds He gave us. In Genesis 1:28 God commanded Adam to subdue the earth. To subdue means to tame and to exercise authority. If we never seek to understand creation or to apply the principles we discover, we cannot be obedient to God's command to Adam.

Renaissance Technology Renaissance technology. As humans began to broaden their fields of knowledge and as education became more widespread, the period of history known as the Renaissance began. With the new desire for scientific study and exploration came a need for new inventions. One of the most momentous inventions in history was produced by a German printer, Johannes Gutenberg. He devised a way to make movable type and so invented the printing press. This invention sped up the printing process and, therefore, made books more readily available. The Bible, the first book printed on the new press, was distributed more widely, and people were able to read it in their own homes. As a result, multitudes of people became more aware of the truth of Scripture. With their desire to understand and follow the Bible came the blessings of God and mankind became more enlightened and productive in every area of life. This is a basic principle of God--He blesses individuals as well as nations through an understanding and acceptance of His Word. As technology in the Middle Ages produced the crossbow, so technology in the Renaissance produced gunpowder. Actually, gunpowder had been invented long before the Renaissance, but knowledge of it was limited to the Chinese. The Western world discovered the existence of gunpowder near the beginning of the Renaissance. However, the skilled use of gunpowder was not common until later in the Renaissance period. In more purely scientific fields, one invention stands out--the microscope. Like the telescope, the microscope enabled scientists to learn about objects they did not know existed. As the telescope made faraway stars and planets visible, so the microscope made tiny, "invisible" organisms visible. The microscope was invented during the late Renaissance by a Dutchman named Antony van Leeuwenhoek, who used his spare time to grind glass lenses. He put two lenses together and examined a drop of water through them. To his surprise, he saw tiny moving organisms which he called "animalcules" or tiny animals. From this simplest microscope, complex light microscopes and electron microscopes were created, making very small objects appear as much as 1,000,000 times larger than they really are. These are only a few of the numerous Renaissance inventions. The Renaissance was a time rich in discovery. We are unable in this limited space to cover more, but you would find your own study of Renaissance technology very interesting. Post-Renaissance technology. In the eighteenth and nineteenth centuries, production of goods for sale in large quantities became an important source of income and trade. The principle of steam power was discovered and applied. Large factories in which goods were turned out on a much larger scale were made possible by steam engines. The steam engine was developed by two men, Thomas Newcomen and James Watt. Newcomen built the first steam engine; unfortunately, it did not work very well. With the improvements added by Watt, however, this engine changed the course of industry. One of the largest industries developed at this time was the textile industry--the industry which weaves and patterns cloth. Cotton was used for cloth long before the Industrial Revolution, but cleaning cotton for spinning into thread was a laborious task. When Eli Whitney invented the cotton gin to separate the seeds from cotton (see figure at right), the production of cotton became rapid enough to provide the large supplies needed by textile manufacturers. Toward the end of the nineteenth century, two men changed the world of industry. Michael Faraday (1791-1867) was a scientist who discovered the principle of the dynamo, or generator, by which electricity could be produced. Faraday is acknowledged as one of the greatest physicists of all-time and is credited with developing the sciences of electricity, magnetism, and electromagnetic induction. From his research, he invented the generator. Faraday also had a continuous faith in the Bible and prayer. Thomas Edison was a technologist who applied Faraday's principles of the generator to his power stations and the light bulb. These discoveries enable industry to be more efficient than it could have been with steam power alone.

Matter and Change Change is all around us. The world is constantly changing. In winter, water changes from liquid to solid on lakes and streams. Clothes on the wash line change from wet to dry. Lead solder changes when heated. Silver tarnishes from shiny to black. Dead plants and animals change with decay. Your body grows and you change to larger clothes. An ice cube melts in the sun. All these examples describe changes in matter. Scientists classify changes in matter as either physical changes and chemical changes. This lesson aims to describe physical and chemical changes; how these changes occur; and how heat is important in many of these changes. Here are your goals for this lesson: Describe and give an example of a physical change Differentiate between a physical and chemical change Explain the effects of heat on matter Describe the processes of evaporation and condensation Distinguish between the heat of fusion and the heat of vaporization Calculate heat energy changes in phase changes of different substances Vocabulary composition The makeup of anything. condensation The changing of a vapor to a liquid. evaporation The changing of a liquid to a gas. Vocab Arcade PHYSICAL CHANGE Have you ever cut wood into small pieces for a fire? Cutting the larger pieces of wood into smaller ones changed the appearance of the original piece of wood. This kind of change is called a physical change. Change in properties. A physical change is a change in the size and shape of a substance. Hardness, shape, mass, and density are physical properties, which may be involved in a physical change. Sodium metal can be cut with a knife because it is very soft. Hydrogen is a light gas. Chlorine is a green gas that is heavier than air. These properties are physical. In a physical change, the kind of matter does not change. No new substance is formed. Therefore, a physical change occurs in the physical properties of a substance without changing its chemical composition. Physical states. All substances exist as a solid, liquid, or gas. Some substances can exist in all three states. For example, when water freezes it becomes ice (a solid). The ice melts and becomes water (a liquid). These temperatures are called melting and freezing points. The melting point of a substance is the temperature at which it changes from solid to liquid. Similarly, the freezing point of a substance is the temperature at which it changes from liquid to solid. Melting points and freezing points are the same temperature. The freezing and melting of water happens at 0°C (32°F). Both phase changes occur at the same temperature. How is that possible? Think of the temperature at which solids and liquids change phase as a door. It is one temperature, but, if approached from one direction, a substance changes from solid to liquid and if approached from the other direction, the substance changes from liquid to solid. When a solid melts into a liquid, it undergoes a physical change. Physical changes do not alter the chemical structure of a substance. For example, when ice cream melts, it still tastes the same. Physical changes also do not change the total mass of the substance. A one-kilogram block of ice will melt into one liter of water. A liter of water is equal to one kilogram. Similarly, if one liter of water is frozen, it will become a one-kilogram block of ice. Have you ever boiled a pot of water to make tea or spaghetti? When the water boils, steam rises from the pot. Why? When temperature is increased to the melting point of a solid, it will change into a liquid. If the temperature is increased even more, the liquid will change into a gas. The temperature at which a liquid changes into a gas is called the boiling point. The boiling point of water is 100°C (212°F). This temperature is also the condensation point of water vapor, or steam. If steam is cooled to 100°C (212°F), it will condense into water. connections Does the word "condensation" sound familiar? Condensation is an important part of the water cycle. When water vapor in the air cools, it changes from a gas into a liquid. The liquid droplets collect onto tiny pieces of dust and other particles in the atmosphere to form clouds. Like melting and freezing points, the boiling and condensation points of a substance are the same. However, the boiling and condensation points for one substance are not the same as for another substance. The boiling point for mercury (Hg), a liquid element, is 356.73°C (674.11°F), much higher than the boiling point for water. Both boiling and condensing are physical changes. They do not change the chemical structure or total mass of the substance. If you were to boil one liter of water, you would create one liter of steam. If the steam were trapped and allowed to cool, it would condense back into one liter of water. Change within a state. If you hold a copper wire in a flame of fire, the wire gets hot; but that isn't the only effect of the heat. If you were to measure the copper wire before and after it was heated, you would find that the heated wire is a little longer and thicker while it is hot. Solids, such as copper wire, expand when heated. The amount of expansion changes according to the type of solid (Figure 1). Liquids and gases also expand when heated. Like solids, different liquids expand at different rates. In general, matter expands as it becomes warmer and contracts, or shrinks, as it cools. Water is an exception in that it expands as it cools from 4°C to its freezing point. You might remember a jar of water cracking as it froze. The jar cracked because the water expanded as it turned to ice. You will recall from the previous unit that all matter has mass and takes up space. The amount of space matter takes up is its volume. The amount of mass in a certain volume is called the density. You can calculate density by dividing the volume into the mass (D = m/v). Heat is involved in many kinds of changes. When heat is removed, most substances contract. A change in temperature causes a change in the density of matter. Adding or taking away heat causes a change in the size of matter. However, adding or taking away heat does not add or take away matter nor change the mass. It is important to note that density changes when heat is added or removed. If a piece of matter contracts, the same amount of matter takes up less space. That is, a greater amount of mass is contained in a certain volume. So when a piece of matter contracts, its density becomes greater. When studying matter, physical and chemical properties are often confused. Below is a table that provides examples of each. Please look them over carefully to distinguish between the concepts that will be covered more fully in the following lessons. Physical Properties Chemical Properties The color of a substance Flammability (reaction with O2) The hardness of a substance A substance reacts with acids Sugar will dissolve in water Silver tarnishes Barium melts at 725º Celsius Helium does not react with other elements Copper can be pounded into a bowl Sodium is stored in oil to prevent contact with oxygen and water The density of water is 1.0 g/mL Iron rusts (reacts) when exposed to oxygen Physical and chemical changes are also a source of misconception. Below is a table that provides examples of each. Please look them over carefully to distinguish between the concepts that will be covered more fully in the following lessons. Physical Changes Chemical Changes Evaporating water from seawater The rusting of an iron nail Moisture in the air forms beads of water on a cold windowpane An electric current changes water into hydrogen and oxygen Oil, vinegar, salt and pepper are shaken together to make salad dressing Yeast cells in bread dough make carbon dioxide and ethanol from sugar Molten brass is poured into a mold and solidifies to form a brass instrument A plant uses the sun's energy, water, and carbon dioxide to produce food.

CHANGE OF STATE Change in state: liquid/gas. If you were to place an open container of water out in the sun, the water would eventually disappear. Why? The liquid water changes into water vapor, a gas. This change from a liquid to a gas is called evaporation. Heat also causes water to boil and change into vapor. Since the molecules of the liquid are in constant motion, they continually bump into each other. As a result of these collisions, the molecules on the surface of the liquid are constantly gaining enough energy to escape. The escaping molecules form a vapor. Water vapor condenses to some degree to form clouds, and eventully rain. Steam is also water vapor. Steam is produced when water is heated to its boiling point. Boiling point can be defined as the temperature at which the vapor pressure of a substance (the pressure the substance exerts to escape into the atmosphere) is equal to the outside atmospheric pressure. At sea level, steam has a temperature of 100oC. The formation of steam is an illustration of the change from liquid to gas. The change from a gas to a liquid is known as condensation. Cooling, or removing heat, causes water vapor to change back into liquid water. This effect can be observed as water forms on the outside of a cold container as water vapor is condensed. SPECIFIC HEAT Substance Specific Heat (cal/g·°C) Water 1.0 Ice 0.5 Glass 0.16 Silver 0.06 State boundaries. Different substances require different amounts of heat to be added (or removed) to produce a certain temperature change. This quality is called heat capacity. Heat capacity is measured by the amount of heat that is needed to raise the temperature of one gram of a substance one degree Celsius. Heat capacity is also called specific heat. The specific heat of several substances is given in Figure 2. In order to better understand the information given in Figure 2, consider the following examples. Notice that liquid water has a specific heat of 1.0 cal/g·°C. This means that it takes 1 calorie of energy to raise 1 gram of water 1 degree Celsius. Ice, on the other hand, only requires 0.5 calories to raise 1 gram of ice 1 degree Celsius. The other substances listed on the table will follow this pattern. What is observed when substances are heated? A common illustration is that of heating ice. Suppose you take one gram of ice at -50° C, slowly heat it, and record its temperature while it is being heated. You also record the amount of heat used. The experiment continues until the ice melts and the water boils. You would find that twenty-five calories are required to raise one gram of ice from -50° C to 0° C. Therefore, the specific heat of ice is about one-half calorie per gram for each Celsius degree. At 0° C, 80 calories of heat are added without causing a change in temperature. During this process, the one gram of ice at 0°C melts and becomes one gram of water at 0° C. Take note that the ice changed to water with no change in the temperature. The 80 calories is the "hidden heat" and is called the latent heat of fusion. Water's heat of fusion is relatively large. Then, as the water continues to be heated, it reaches 100° C. 100 calories were needed to reach this temperature. You will now find that 540 calories of heat are needed to convert the water to vapor at 100° C. This hidden heat associated with boiling is called the latent heat of vaporization. The latent heat of vaporization of water is one of the highest known. Heat of fusion for water = 80 cal/g Heat of vaporization for water = 540 cal/g Heat energy changes can be summarized by showing the formulas for each. Note: the character Δ, or Delta stands for change in a condition, for example ΔT means change in temperature. It is important to note that when solving for heat energy, the density of a substance is important to know to convert any volume in mL to grams. The density of water is 1g/mL. This conversion factor is needed to solve problems involving water. For example, if you have 50 mL of water, this is equal to 50 grams of water. Although mL is most often used for volume of liquids, you will see density values given in g/cm3 as well. Usually cm3 is used to measure the volume of a solid. The two are interchangeable. To summarize: 1 mL = 1cm3 1 g/mL water = 1 g/cm3 water Heat energy formulas If heat energy is being added and there is a temperature change then, ΔH = specific heat (c) x mass x ΔT Example: How much heat does a 25.0 g ice cube absorb as its temperature increases from -16.4°C to 0.0 °C? 0.5 cal/g·°C x 25.0 g x 16.4°C = 205 cal If heat energy is being used to change from a solid to a liquid then, H = H fusion x mass Example: How much heat energy is needed to melt a 65 g cube of ice? 80 cal/g x 65 g = 5200 cal If heat energy is being used to change from a liquid to a gas then, H = Hvaporization x mass Example: How much heat energy must be applied to 100.0 mL beaker filled with boiling water in order to vaporize it all to steam? Remember that the density of water is 1 g/mL, therefore, 100.0 mL of water is equal to 100.0 g. 540 cal x 100.0 g = 54,000 cal or 5.400 x 104cal, due to significant figures. Heat changes in chemical and physical processes can be measured using an insulated device called a calorimeter. In a calorimeter, the temperature change of a known mass of water is used to determine the amount of energy released or absorbed by a system undergoing a chemical or physical change. When ice is added to water at room temperature, the water provides the energy for two processes. The first process is the melting of the ice. The energy needed to melt the ice is the heat of fusion (Hfusion). The second process is raising the temperature of the melted ice from its initial temperature of 0.0°C to its final temperature of the liquid water.

Solutions Another kind of physical change takes place when two substances are mixed together. For example, when you mix sugar in water, you make a solution. In making a sugar-water solution, the molecules of sugar become separated from each other and become scattered among the water molecules. When the sugar and water molecules do not combine chemically, the sugar dissolves in the water. The physical property of being able to dissolve is called solubility. A substance that does not dissolve in a liquid is insoluble. Here are your goals for this lesson: Recognize the difference between homogeneous and heterogenous mixtures Differentiate between solutions and mixtures Distinguish between colloids and suspensions Vocabulary aqueous Any solution with water as the solvent. colloid A heterogeneous mixture whose particles never settle. dissolve To break up into molecular parts and go into solution. heterogeneous mixture A mixture of different substances that are unevenly distributed and are easily identified. homogeneous mixture A solid, liquid, or gas mixture that contains two or more substances blended evenly throughout. immiscible A condition in which one liquid is not soluble in another liquid. miscible the ability of certain liquids to dissolve in each other. mixture A combination of two or more substances that are not chemically bonded and retain their own properties. saturated The situation when a solution has dissolved all the solute it can at a given temperature. soluble Capable of being dissolved into a liquid. solute The substance being dissolved. solution A homogeneous mixture whose particles are too small to reflect or scatter light. solvent The substance that the solute is dissolved in. supersaturated A solution that holds more solute than it normally can under the conditions at a given temperature. suspension A heterogeneous mixture containing a liquid in which visible particles settle with time. unsaturated A solution which is able to dissolve more solute. Vocab Arcade Solutes and Solvents. In a sugar-water solution, sugar is known as the solute, the substance that is dissolved into the solution. The water is the solvent, the substance that does the dissolving. Water is known as the "universal solvent" based on its ability to dissolve more substances than any other solvent. Any solution in which water is the solvent is referred to as an aqueous solution. Can you think of some other examples of solutions, naming their solutes and solvents? What about carbonated beverages like soda? A carbonated beverage is actually made from a solution of water and carbon dioxide. Does it surprise you that a liquid can combine with a gas to form a solution, as in soda? Did you know that all three states of matter can act as a solute or solvent to form a solution? Solids can dissolve in gases, liquids or other solids. Liquids can dissolve in gases, solids, or other liquids. Gases can dissolve in solids, liquids, or other gases. That makes nine possible solute/solvent combinations to form a solution! Mixtures and Solutions. It is important to remember that not all mixtures are solutions. A mixture of sugar and water forms a solution because the sugar dissolves into the water. On the other hand, a mixture of sand and water does not form a solution. What are the differences between these two mixtures that allow one to be a solution while the other is not? If a mixture is homogeneous, it can be referred to as a solution. A homogeneous mixture maintains a uniform appearance and composition. Homogeneous substances often exist as only one phase--all liquid, all gas, or all solid. Unlike homogeneous mixtures, heterogeneous mixtures often exist as two or more phases. As a result the two mixed substances can usually be told apart; for example, in a glass of soda, the carbon dioxide gas bubbles are visible as they move up through the liquid water and escape. Consider sugar and water again. If you drop a tablespoon of sugar into a beaker of water, the two together are not immediately a solution. Each substance in the mixture is visible and in a different phase from the other. You will see a lump of solid sugar on the bottom of the beaker and liquid water throughout the beaker. This is a heterogeneous mixture. In order to make this mixture into a solution, you must find a way to make the mixture homogeneous. In this case, simply stirring the mixture will do. After a short time you will no longer see the sugar, since it has dissolved into the water. You now have a homogeneous solution. The entire solution is a clear, sweet tasting liquid! Have you ever poured some oil into a bottle of water? Oil in water is a mixture, but not a solution because the mixture is heterogeneous. Even though oil and water are both liquids, neither substance dissolves the other. They do not mix together to form a homogeneous substance. Instead oil floats on top of the water. This mixture can be referred to as immiscible because it will not form a solution and because the water and oil are insoluble in one another. Even if you vigorously shake a bottle of oil and water, the two liquids will not form a solution. The oil may break apart forming little "balls" of oil surrounded by water, but the two will never mix like the sugar and the water do. This is an example of substances of the same phase remaining heterogeneous. If oil and water are immiscible because oil will not dissolve in the water, does that make sugar and water miscible because the sugar does dissolve in the water? Although this appears to make sense, sugar and water are not considered miscible. In order to be miscible, the two substances in the solution must be of the same phase. Vinegar is an example of a miscible solution because it is the product of acetic acid and water. Both of these substances, the acetic acid and the water, are liquids. Since they are the same phase and the acetic acid dissolves completely in the water, these two substances are considered miscible. Saturation. You have probably heard of the terms saturated and unsaturated before, but do you know what they mean in reference to solutions? At a given temperature, a solvent can only dissolve so much of a particular solute. When a solution reaches the point where it contains all the solute it can possibly hold, it is considered saturated. Anything under this point is considered unsaturated. For instance, if you stirred a little sugar into water and all the sugar dissolved, the solution would be unsaturated as long as you could keep adding and dissolving more sugar. At some point, if you kept stirring more and more sugar into the water, some of the sugar would remain in a clump on the bottom of your container no matter how much stirring you did. The sugar-water solution would now be considered supersaturated. A solution that is supersaturated contains more solute than can be dissolved at a given temperature. Colloids and Suspensions. Some mixtures appear to be homogeneous solutions when they are actually heterogeneous mixtures. Colloids are mixtures which contain particles that are intermediate in size between solutions and suspensions. The particles in a colloid remain evenly distributed without settling out. The particles are so small that they are not visible without the aid of a microscope. Therefore, a mixture appears to be homogeneous when it is not. Fog and milk are examples of colloids. Fog appears to be a homogeneous solution when in reality it is a colloid made up of air and water droplets. Colloids come in many forms, including aerosols, sols, emulsions, and gels. Aerosols are made of solid or liquid particles in a gas, such as fog. Sols are solid particles in a liquid, such as milk of magnesia. Emulsions are liquid particles in liquid. Mayonnaise is an emulsion that is oil in water. Gels are liquids in a solid, such as gelatin. Suspensions are similar to colloids except that the particles in suspensions are big enough to be visible to the naked eye. A suspension may be shaken and the particles will be evenly distributed for an amount of time, but will eventually settle out. Salad dressings are suspensions. Some medicines prescribed by your doctor are also suspensions, thus the label will tell you to shake before using. Help Farmer Frank get off the ground by reviewing what you've learned.

Chemical Changes If you chop a large piece of wood into smaller pieces, the wood is obviously changed in appearance. Yet this change is only a physical change because each of the smaller pieces of wood is exactly the same kind of matter as the larger piece of wood. Other kinds of changes can be made that change the chemical composition of matter. This section will discuss some of these chemical changes as well as some examples. Here are your goals for this lesson: Distinguish between a physical and chemical change and provide an example of each List some indicators of a chemical change Explain the Law of Conservation of Mass Recognize that the number of atoms of each element is conserved in a chemical reaction Interpret a chemical equation Define and provide an example of oxidation Balance a chemical equation Describe the difference between coefficients and subscripts in a chemical equation Vocabulary endothermic A chemical reaction that takes in heat. exothermic A chemical reaction that gives off heat. oxidation Process of combining an element with oxygen. product The end result of a chemical reaction. subscript Written underneath or below. Vocab Arcade Chemical properties. The properties of a substance tell how it reacts with other substances. Some substances, for example, combine with oxygen and burn. The chemical properties of a substance always describe how it unites with other substances. Changes in chemical properties are called chemical changes. In a chemical change, new substances are produced. Burning wood and rusting iron are chemical changes. A comparison of physical and chemical changes is shown in Figure 5. Have you ever seen a flashbulb used? The bright light from a flashbulb is the result of a chemical change. A flashbulb has a fine wire inside. This wire is usually made of magnesium. When the flashbulb is used, oxygen inside the bulb combines with the magnesium to produce a white powder called magnesium oxide. This reaction of magnesium (Mg) and oxygen (O) to form magnesium oxide (MgO) also produces heat and light. Magnesium is also used in fireworks and signal flares. If you burn wood, definite and permanent changes occur. The wood changes into ashes, water vapor, and other gases. The molecules of the ashes, water vapor, and other gases are different from those of the wood. Thus when wood is burned, the kind of molecules in the wood are changed. This change is also a chemical change. Chemical changes usually involve the release of heat, light, water, or electricity. Energy is either absorbed or given off during a chemical change. If energy is given off, the reaction is called exothermic. If heat or energy is taken in during the reaction, it is called endothermic. Molecular structure. Water is comprised of oxygen and hydrogen. At most temperatures, oxygen and hydrogen are gases. The elements hydrogen and oxygen exist in nature as diatomic molecules. This means that hydrogen exists as H2 and oxygen exists as O2. What happens to the atoms of these gases when water is formed? One way to answer this question is to say that the oxygen atoms and hydrogen atoms join together to form water molecules. However, in their molecular state, both oxygen and hydrogen molecules combine to form water molecules. Figure 6 shows how this combination happens. Count the number of atoms--mass is not lost or gained. Each atom is shown as a circle. Each circle is labeled with a chemical symbol, H for hydrogen and O oxygen. Molecules are shown as two or more circles together. This represents a chemical change because the molecules are different from the original molecules, thus there is a change in composition. If you count correctly, you find that the numbers and kinds of atoms present before and after are the same. Only the molecules change in most kinds of reactions. Chemical reactions. Burning and rusting are two common chemical reactions. In chemical reactions new substances are formed and heat and light may be given off. When iron rusts, the iron reacts with oxygen to form iron oxide. The element iron changes to the compound iron oxide by combining with oxygen. This is called a synthesis reaction or sometimes referred to as a combination reaction. Synthesis reactions are most often exothermic, giving off heat to the surroundings. When this occurs, the physical properties of the iron oxide compound are different from the original element. The mass of the oxide is equal to the combined mass of the iron and oxygen. Mass is neither lost nor gained in the reaction. In ordinary chemical changes, no matter is lost. The mass of all the substances before a reaction equals the mass of all the substances after the reaction. This principle is called the Law of Conservation of Matter and is a basic principle in studying chemical reactions. The opposite of synthesis is decomposition. It occurs when a compound is broken down into its component parts, either simpler molecules or elements. The electrolyis of water is a decompostion reaction and requires energy input, therefore it is an endothermic reaction. Water is broken down into its component elements, hydrogen and oxygen. The products have different chemical properties than the starting reactant, water. Decomposition reactions also follow the Law of Conservation of Matter as seen below in the reaction equation. 2H2O(l) → 2H2 (g) + O2 (g) The Law of Conservation of Matter can easily be seen when describing a chemical reaction by use of an equation. A word equation tells you what substances are involved in the reaction and the names of the newly formed substances. A word equation does not tell you how much of each substance is involved in the reaction. For example, the chemical change involved in a flashbulb or fireworks is represented by the following reaction: The arrow ( ) means yields. The word equation above would then read, "magnesium plus oxygen yields magnesium oxide." It is helpful to know how much of each substance is involved in a chemical reaction. The substances always combine in the same proportions for a reaction to be completed. In the reaction of magnesium and oxygen, atoms of magnesium combine with atoms of oxygen to make molecules of magnesium oxide. A chemical equation is like a word equation except that numbers and symbols are used in place of words. The chemical equation for the reaction between magnesium (Mg) and oxygen (O) is this: The number before a symbol shows the number of molecules or atoms that take part in the chemical change. A symbol represents one atom of the element. Look at the equation above. The 2 in front of the Mg symbol represents two atoms of magnesium. These atoms combine with one molecule of oxygen (O2). The subscript 2 in O2 means that two oxygen atoms make up the oxygen molecule. The substances which unite are called reactants. The substances which are produced are called products. Another example of a chemical reaction is rusting. This chemical equation tells that four atoms of iron (Fe) combine with three molecules of oxygen (O2). This equation also shows the ratio of atoms and molecules that combine. Be sure to notice that the three molecules of oxygen (3 O2) amount to six atoms (3 × 2) and the total number of iron atoms is four (4 × 1). Therefore the total number of atoms of reactants is ten. Since mass is neither lost nor gained, ten atoms must appear in the product (two iron atoms + three oxygen atoms times 2 = ten). The product of this reaction is iron oxide (rust). When the number and kind of atoms on the left side of the arrow equal the number and kind of the right side, the equation is balanced. You may never change a subscript to balance an equation; only change coefficients. Oxidation processes. A chemical change in which an element or compound unites with oxygen is called oxidation. Rusting is an example of slow oxidation. The flash of fireworks is rapid oxidation. Burning is also rapid oxidation. Burning is a chemical change in which the atoms of a substance rapidly combine with atoms of oxygen to form new substances. Heat is always given off in the oxidation process. Sometimes a fire starts because of a buildup of heat from slow chemical changes. A slow buildup of heat from oil in rags may occur as the oil is oxidized by oxygen. The slow oxidation of the oily rags eventually results in a rapid oxidation if the rags burst into flames. Because the fire is started without any apparent help, it is called spontaneous combustion. When a candle is lit, the chemical change produces water vapor (H2O), carbon dioxide (CO2), and carbon monoxide (CO). Black carbon is another by-product of a burning candle. An explosion is also a chemical process of oxidation. Explosions are caused by instantaneous combustion and can be dangerous. Mixing or playing with chemicals without adult supervision can result in an explosion. Read the reference section in this unit for guidelines concerning safe experimentation.

Mixtures If you have ever fixed a bowl of cereal and milk, you have made a form of matter called a mixture. In a mixture, two or more elements or compounds are mixed together, but not chemically joined or combined. They are simply mixed together. If you look at a broken piece of concrete, you can see different sized pieces of rock and grains of sand. The rocks and sand were mixed together in a hardening material. They are a mixture, not a compound. Here are your goals for this lesson: Define mixtures Provide an example of a mixture Vocabulary alloy A mixture or solid composed of two or more metals melted together. Vocab Arcade It is not as easy to determine other mixtures. Sometimes you may not be able to see the different substances in a mixture. A sugar-and-water mixture, for example, might look like just water. Mixtures that appear to be the same throughout are called solutions. Solutions can be solids, liquids, or gases. Air is a solution of gases. Sterling silver is a solid solution. Pure silver is too soft to be used. It is melted and mixed with other metals, like copper, to make it stronger. The melted metals cool to form a solid solution called an alloy. Keep in mind that not all metals are mixtures. Some metals, like gold, platinum, and lead, are simple elements.

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Today's Scientist Since the beginning of time, people have been observing his or her surroundings. We have seen how philosophers like Aristotle formulated ideas about the world. People of God also observed the magnificence of God's creation. David said, in Psalm 139:14, "I will praise thee; for I am fearfully and wonderfully made: marvellous are thy works; and that my soul knoweth right well." People are still amazed at the beauty and order of creation, but his or her method for formulating ideas about his or her world has changed. As science advanced, people learned to use procedures for verifying scientific theories, in contrast to people like Aristotle and Democritus who arrived at their conclusions through the use of logic. Logic and reasoning do not always correspond to the truth, particularly for fallen people who do not rely on Scripture for guidance. In this section you will learn more about the methods and tools of the modern scientist. Here are your goals for this lesson: List and describe the steps involved in the scientific method State the four defined units of the metric system Write any numeral in scientific notation and change any scientific notation back to a numeral Determine the number of significant figures in a number Demonstrate the ability to add using significant figures Vocabulary experimentation Doing repeated tests to prove a scientific fact. exponent The number of times a base number is multiplied times itself, shown as a superscript following the base number. hypothesis A proposed answer to a specific scientific problem. law A proven scientific fact which has never been falsified or an exception observed. liter The standard metric unit of volume. meter The standard metric unit of length. metric system A system of measurement based on the number ten. scientific method The ordered steps a scientist uses in his or her work. scientific notation A system of writing numbers as a multiple of a power of 10. second The standard unit of time. significant figures Those digits in a number that have true value. theory A suggested or proposed solution to a general scientific area of inquiry based upon a series of experiments or interpretation of observed data. Vocab Arcade THE SCIENTIFIC METHOD For a scientist to work effectively, it is necessary that he or she follow a system of steps as he or she approaches each new problem. Variations on this system of steps have been composed, but they all cover the same procedures. The steps of the scientific method in this unit may be somewhat different from the steps you have seen somewhere else, but you will find that the same basic order is followed. The first step is, of course, to choose a problem. This step seems simple; but when you try it, you find it can be surprisingly involved. The problem must be one you have the ability to solve, one that interests you, and one that is worth the time to solve. Some problems are so unimportant that you would be wasting your time trying to solve them. The second step is to state what you think is a possible solution to the problem. This potential answer is called a hypothesis. When you have stated a hypothesis, you must research what other scientists have done to solve your problem or other similar ones. You may find that someone else has already solved your problem, or you may find that another person's research will simplify your work. Having collected and recorded all the information you can, experiment to prove or disprove your hypothesis. All of the data from the experiment must be carefully recorded if it is to be scientifically acceptable. It is necessary to have these experiments repeated again and again, either by yourself or with other scientists. To facilitate this, your findings must be published in a scientific journal for peer review. It is often easier to disprove a hypothesis than to prove it. Results showing a hypothesis to be false are more conclusive. Usually, an experiment designed to prove a hypothesis can only appear to prove it because absolute proof is not always possible. If your hypothesis proves to be correct through repeated experimentation, it then becomes a theory. A theory is more sure than a hypothesis, but it has not been tested enough to be proven beyond all doubt. A theory may involve a broad area of research and may require several problems or hypotheses to be investigated by the scientific method. A series of proven hypotheses from independent experiments may lead to a generally accepted theory. Should your hypothesis be falsified or found to be in error, you must state a new hypothesis and start over. When considering observations and their related hypotheses, applying the scientific method to them gives us a level of certainty. Sometimes new facts will be discovered which prove a theory wrong. Always keep enough doubt in your mind about your theory so that you can change it should it be proved wrong. Theories and laws can be a bit confusing to separate from one another. A theory does not become a law because a law and theory are different. Law's explain "what" happens and theories explain "why" it happens. Laws have been found to be true in all cases up to this point in time and theories often evolve and change slightly with new observations and data. That is not to say a law cannot be disproven. It may at some point in time be proven to not be true in all cases. In the case of Newton's law of gravitation, it is a law because it states "what" happens, but his law was never a theory because it never explained "why" it happens. Therefore, we can make predictions based on Newton's law, but we can't explain that behavior based on his law of gravitation. Remember, for scientific work always follow these or similar steps. Without them your work will be unreliable, because it will be neither orderly nor conclusive. SCIENTIFIC MEASUREMENT Three kinds of scientific measurement will be presented in this section: (1) the metric system, (2) scientific notation, and (3) significant figures. Metric system. The scientist works with numbers almost as much as a mathematician does. Measurement and mathematics are a vital part of science. To make mathematics as simple as possible, the scientist uses the metric system almost exclusively. For our purposes, the metric system has four units that are defined; all other units are derived from these defined units. The standard units are: volume liter length meter mass kilogram time second Each unit has divisions and multiples, just as an inch is a division of a foot and a yard is a multiple of a foot. The metric system is simpler to use, however, its divisions and multiples are based on the number ten. Here are a few commonly used examples, with the standard unit shown in boldface. *The National Bureau of Standards (spring, 1978) has standardized the abbreviation of liter as L (with no period). You will be working with metric units, so learn them well. They are necessary tools of the scientist. Scientific notation. Sometimes, scientists must work with very large numbers. To make their work easier, they use a kind of mathematical shorthand called scientific notation. Do not allow the long name to stop you. The system is not as difficult as its name would lead you to believe. Like the metric system, it is based on the number 10. To write a number in scientific notation begin by writing the far left digit. Let us use the number 200 as a model: First write the 2. Then write a multiplication sign. Then write the number 10: 2 × 10 Then count the number of digits after the 2 in 200. There are two zeros. Place a small 2 above and to the right of the 10. This 2 is the exponent. 2 × 10 2 This mathematical expression is read two times ten to the second power, or ten squared. Scientific notation is writing a number less than ten times a power of ten. It is a little more involved to write in scientific notation a number that has more than one digit which is not a zero. Using the number 528 as a model, first write the far left digit. Then place a decimal point after the 5. Then write the other two digits in order. Then add the multiplication sign and the 10. (The number to be multiplied by 10 raised to a power is always between 1 and 10. In this case, the number is 5.28, not 0.528 or 52.8.) 5.28 × 10 Now, count the number of digits after the decimal point in 5.28. There are two of them, 2 and 8; therefore, place a small 2 above and to the right of the 10. 5.28 × 10 2 We read this sentence as five and twenty-eight hundredths times ten squared. (Often we use a short cut and say five point two eight times ten squared). A number having more than three digits is read slightly differently. For example, the number 1,248 would be written 1.248 × 10 3. It is read one point two four eight times ten to the third power or times ten cubed. The number 48,691.2 is written 4.86912 × 10 4 and would be read four point eight six nine one two times ten to the fourth power. In converting any number into scientific notation, remember that the decimal place is assumed to be at the end of a whole number, even though it is not written. Therefore when converting, start moving the decimal point from its original location, regardless of whether it is a whole number or it contains an existing decimal. Numbers having only one or two digits are not written in scientific notation. To work back to numerals from a number written in scientific notation is not difficult. For instance, consider 4 × 105 as a model. First write the digit 4. Then look at the exponent of ten; it is 5, so write five zeros to the right of 4. Now count back 3 zeros from the right and place a comma. The number is four hundred thousand. 400,000 Again, consider the number 6.2 × 104. This model is a bit different, so follow the steps carefully. First write the 6. Now look at the exponent of ten. It is 4. A total of four digits will be written to the right of the six. The 2 is the first of the four. Now add three zeros to complete the four digits. Next, count back three digits from the right and place a comma. The number is sixty-two thousand. 62,000 Following these simple steps, you should be able to write any numeral in scientific notation and change any scientific notation back to a numeral. Significant figures. To be accurate with scientific measurements, a measurement should be as close to the actual measurement as possible. An example of accuracy may be given in a science laboratory. Imagine a group of students is asked to find the mass of a substance that a teacher has already determined the mass to be 5.65 grams. The four students in the group present their findings to the teacher. The first student reports that the mass is 5.93 grams, the second student reports that the mass is 6.12 grams, and the third student reports that the mass is 6.05 grams, the fourth student reports that the mass is 5.55 grams, which student has the most accurate answer? The student that is closest to the actual measurement is the most accurate, therefore, the fourth student's measurement of 5.55 grams is closest to the actual measurement of 5.65 grams and is the most accurate. Precision is closely related to accuracy and can be easily confused with it. The word 'precision' is defined as 'the degree of exactness in a measurement.' Precision is a means to describe the limits of a measuring instrument and how many significant figures can be used in the measurement.The smallest gradations on a centimeter ruler are usually millimeter markings. This means you can measure precisely down to the millimeter level. It has been agreed upon in the scientific community, however, that when using a calibrated scale (such as a ruler), you should estimate one digit beyond the level of the markings. If using a centimeter ruler with millimeter markings this would mean you should estimate to one digit beyond the millimeter level, or 0.1 millimeters (if you are recording your measurement in millimeters). If you are recording your measurement in centimeters, you should estimate to 0.01 centimeters, or to two decimal places. Your measurement would then contain the correct number of significant figures. We know that every number is composed of digits. For example, consider 6,432 centimeters. The last number, 2, shows that the object is at least 6,431 centimeters in length and not more than 6,433 centimeters in length. The 2 is not as certain as the 6, 4, and 3; it is estimated. The number 6,432 has four significant figures, but the last digit is only estimated. If we wanted to show that the last digit was absolutely certain, we would write 6,432.0 instead. Significant figures needs to be carried through in calculations as well. Scientists often work with several large numbers at one time. Perhaps a scientist needs to add a list of quantities. Note this problem: The answer is 46.6778 grams, but how much of that answer can be considered precise to the correct amount of significant figures. Just as a chain is only as strong as its weakest link, so an answer is only as precise as the least precise of its components. The number from the list of quantities with the least precision of measurement is 4.1 g. It has only one significant figure right of the decimal point. Thus, the answer 46.6778 g is precise only to one decimal place. The answer would be rounded off to 46.7 g, this shows the correct precision and the correct number of significant figures. Below are a couple more examples of addition and subtraction with significant figures. Examples: 3.45 cm + 0.781 cm = 4.231 cm but rounds to 4.23 cm because of SF (significant figures). 789.58 g - 21 g = 768.58 g but rounds to 769 g because of SF. Multiplication and division have a slightly different rule. The number of significant figures in the answer to a multiplication or division problem should be no more than the least number of significant figures in any of the figures being multiplied or divided. Let's look at some examples of this. Example: Multiply (46.39 cm) x (65.4 cm) 46.39 cm has four significant figures and 65.4 cm has three. Our answer must have three digits since the answer has to reflect the fewest significant figures of any in the problem. (46.39 cm) x (65.4 cm) = 3033.906 cm2 and rounds to 3030 cm2 or 3.03 x 103 cm2 Example: Divide (569.0 g) / (65 mL) 569.0 g has four significant figures and 65 mL has two. Our answer must have two digits since the answer has to reflect the fewest significant figures of any in the problem. (569.0 g) / (65 mL) = 8.75384....g/mL and rounds to 8.8 g/mL. Note that the third numeral is a 5, thus the 7 preceding is rounded to 8. It should be noted that the significant figures rules only apply to measurements, not constants or counting numbers. Counting numbers and defined constants have an infinite number of significant figures. Therefore, only use measurements to determine the number of significant figures in an answer. There are many constants used in science, some constants include gravitational constant, pi (π), speed of light, speed of sound, Planck's constant, atomic mass units, electron mass, proton mass, etc...Let's try an example calculation using a constant. Example: The acceleration of gravity on Earth is 9.8 m/s2 (this is a constant). If a person's mass is 215 kg, what is the person's weight on Earth measured in newtons (N)? The formula used: (gravity) x (mass) = weight (9.8 m/s2) x (215 kg) = 2107 N = 2110 N or 2.11 x 103 N The answer needs three significant figures due to the measured mass in the problem, NOT the acceleration of gravity. The rules for significant figures can get pretty confusing at times. It takes practice and time. Numbers greater than 1. In a number ending in zeros, the ending zeros are not counted as significant figures. For example, 760 and 2,600 have only two significant figures each. Zeros are simply place holders unless the decimal point is used. Zeros placed to the right of the decimal after a number are also significant figures. For example: 2,600.0 has five significant figures. 7.600 has four significant figures 18.20 has four significant figures 6432.0 has five significant figures Numbers less than 1. For numbers which are less than one, zeros are just place holders if they occur between the decimal and the number; for example, .0077 has just two significant figures. .0136 has just three significant figures. .005 has just one significant figure. .0050 has just two significant figures. .00510 has just three significant figures. Note: 1.005 is greater than 1; therefore, it would have four significant figures. Click here for more help on significant figure rules and mathematical operations.

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Properties of Matter ( 1 ) The Greek philosophers of the third and fourth centuries were great thinkers, and they thought about matter and problems that are studied even today. They asked questions like: If you divide a cup of water in half, then divide it in half again and again, do you ever run out of water and end up with something else? The thinkers of ancient Greece tried to reason things out without doing experiments. As a result, not all of them got the same answers. The man who came closest to our modern view of matter was Democritus, who lived about 460 B.C. He believed that all matter was composed of a large number of small objects which he called atoms (this Greek word means indivisible). Democritus thought these objects were all composed of the same material but came in different shapes and sizes. Aristotle believed that all matter was composed of four things: earth, fire, air, and water. He disagreed with almost all of the ideas of Democritus. Ideas changed very little until the seventeenth century when such scientists as Robert Boyle and Isaac Newton developed new theories about matter. These people experimented and developed the atomic theory. This theory states that matter is made up of atoms, which act as building blocks for all matter. Today, with the aid of the electron microscope and other modern technology, molecules can be "seen;" models of particles even smaller than atoms have been set up. Throughout the centuries people have attempted to unravel the inner secrets of matter, of all that God has so perfectly and wonderfully created. Here are your goals for this lesson: Define and describe the two fundamental properties of all matter Describe the ways matter can be classified Explain how to use mass and volume to find the density of an object State Archimedes Principle Distinguish between boiling point and freezing point Vocabulary atom The smallest part of an element that can exist alone. balance An instrument for determining mass. buoyancy The tendency of a body to float in a fluid. Celsius scale The temperature scale with water freezing at 0° and boiling at 100°. centigrade The temperature scale with 0° at freezing and 100° at boiling. Same as Celsius. classify To assign to a category. cubic Having the form of a cube. density The mass of a substance per unit of volume. displace To remove from the usual place. Fahrenheit The temperature scale with water freezing at 32° and boiling at 212°. linear Having the properties of a straight line. mass The amount of matter in an object. meniscus The curved top surface of a liquid column. molecule Two or more atoms chemically combined. volume Space occupied, measured in cubic units. Vocab Arcade Scientists study the world around us to learn how materials are alike and different. Some of the differences in matter are easy to see; some are not. Every kind of material has at least one property that makes it different from other materials. For example, glass can be used for most cookware while plastic cannot. The materials used to make a lock have special properties. What property explains the rust on a piece of metal? Can matter be changed from one kind to another? These questions and others are answered by studying the properties of matter. GENERAL PROPERTIES OF MATTER How is all matter alike? There are two basic properties that all matter shares. Volume. The first general property of matter is that it takes up space. No two units of matter can take up the same space at the same time. One unit must move. If you have ever dropped something into a full pail of water, you might have noticed that some of the water flowed over the edge of the pail. Whatever was dropped into the pail took up some of the space that had been filled by the water. As a result, some of the water was displaced from (pushed out of) the pail. Air can also push water out of one place and into another. The amount of space that matter takes up is called the volume of that matter. Thus, a giant boulder has more volume than a small rock. However, any unit of matter, large or small, solid, liquid, or gas, takes up space and therefore, has volume. You can determine the volume of an object in two ways: 1. For an object of uniform shape having linear sides or a common geometric shape (e.g., a block of wood, a brick, or a cylinder), measure the object and determine the volume mathematically. 2. For an irregularly shaped object that cannot be measured easily or does not consist of uniform geometric shapes (e.g., a horseshoe or a blob of silly putty), determine the volume of water it displaces. The volume of water displaced equals the volume of the object, as long as the object does not absorb or dissolve in water. When measuring the volume of water in a graduated cylinder or similar container, be sure you read the lowest point of the curved surface of the water, the meniscus. Study Figure 1 to find the correct level. Mass. If you were to lift a small stick and a large rock, you could tell quickly which one was heavier. This experiment would tell you about another general property of matter. All matter on earth has weight. When you weigh something, you are measuring the pull of the earth's gravity on that object's mass. Why do some things weigh more than others? The reason is that some things have more matter in them than others. The amount of matter in an object is called the mass of that object. Mass is measured in kilograms in the metric system, but grams is also commonly used when working with smaller amounts. The more mass an object has, the more it will weigh. Keep in mind that the terms mass and weight are defined differently. Remember that weight changes slightly with altitude or position on the earth. Weight on the moon is substantially different than weight on earth. The reason is that the force of gravity changes as you get farther away from the core of the earth. This is easily seen on the moon. The force of gravity on the moon is about 1/6 of that on earth. Thus, if you travelled to the moon you would weigh less, however your mass would remain the same, because gravity does not affect mass. Mass is always a constant, meaning it never changes. Because the weight of an object is not constant, merely weighing an object will not determine its mass. If you are using the correct units you can determine an object's mass by taking the object's weight and converting it to mass by using a conversion factor. 1 pound in the English system is equal to 454 grams or 0.454 kg. Thus, a person weighing one hundred pounds has a mass of 45.4 kg. This is done by simply multiplying the pounds by the .454 kg/lb. Pounds will cancel and the new unit is kg. A sample problem is given below. In this problem a person weighs 212 pounds and we are looking for his or her mass. The mass of an object may also be determined by placing it on a balance scale and comparing it with a known standard mass (the kilogram [kg]). SPECIAL PROPERTIES OF MATTER We know that all matter must possess mass and take up space. There are other properties that can help us learn what makes each substance different from others. Knowing the shape, odor, taste, color, density, buoyancy, freezing point, and boiling point of a material will tell us what the substance is like. These properties are called special properties. These special properties tell us a great deal about the ways a substance may react or be used. For example, you may have three beakers full of different liquids; one contains plain water, one contains grape soda, and one contains white vinegar. All three liquids have mass and take up space. How can we tell them apart? One way is to classify the three liquids according to their special properties. The soda can be distinguished from the other two by its color and taste. The water and the vinegar look the same but can be distinguished from each other by odor, taste, and boiling point. We can also find out many of the special properties of a substance by looking at a table or chart outlining this kind of information. Knowing the differences of matter helps classify things. Since all matter has mass and takes up space, the special properties are important for us to know. Density. Density is an important special property of matter. Density is the mass of a substance per unit of volume. In the metric system, volume is measured in liters, milliliters, or in the case of the figure to the right, cubic centimeters (cm3). Density may be expressed in grams per cubic centimeter (g/cm3). For example, water has a density of 1 gram per cubic centimeter. 1 cubic centimeter is equal in volume to 1 milliliter so they can be used interchangeably. Often, milliliter is used when referring to the density of a liquid or gas and cubic cm is used when referring to density of a solid. You will experience the use of both in the future, but both are referring to the same thing. The important thing to remember when looking at units for density is that it is a unit of mass over a unit of volume. For instance, the density of water can be written as 1g/cm3 or 1g/mL. Have you ever heard the riddle, which is heavier, a ton of bricks or a ton of feathers? The answer of course is they are both the same, but if we asked which is more dense, a ton of bricks or a ton of feathers? We would have to think differently, because now we have to consider the volume used up by the feathers and the bricks. Think on it before reading on. Ask yourself, would a ton of bricks take up much space? Or, would a ton of feathers take up more space? I hope you will agree, but even if we compressed the feathers into smaller containers, the bricks would take up less space and space is volume. Therefore, the density of bricks is larger than the density of feathers. Consider another example; if we compare two marbles of the same size (volume), but one is made of aluminum and the other is made of iron, which is heavier? Hint: look at the table of substances and density, you will find both iron and aluminum listed there. Which has the higher density? The answer of course is iron. It has a density that is almost 3 times greater than that of aluminum. So, can you answer the first question, which marble has more mass? The iron marble will feel heavier because it has more mass. To find the density of a substance, you must first know its mass and volume. Figure 2 lists densities of some common substances. Note: This and other answers may be printed as 2g/cm3. This format is used by some computers, printers, and calculators solely to keep the text on the same line. BUOYANCY Why do some things float? You already know that heavy objects tend to sink, and light or hollow objects tend to float. Floating is related to density. Paper, cork, wood, and some plastics float on water. Each of these substances has a low density. A piece of steel will sink to the bottom, but a merchant ship made of steel will float. Why? When an object is placed into a liquid, it pushes that liquid aside. The object displaces the liquid, or moves it, to another place since both substances cannot occupy the same space at the same time. When you get into a bathtub, you probably notice that the water level rises. Your body is displacing or pushing aside a certain amount of water. If the mass of the amount of liquid displaced is equal to the mass that displaced it, the object will float. This law, or principle, is named for Archimedes, the Greek philosopher who discovered it. It is sometimes referred to as Archimedes' Principle. When a block of wood is placed in water, it sinks until an amount of water exactly equal to the mass of the block is displaced. The water underneath the wood exerts a push or force to hold it up. This upward force is called buoyancy. Freezing and boiling points. The temperatures at which a substance boils or freezes are special properties of matter. The freezing point is the temperature at which a liquid changes to a solid. The boiling point is the temperature at which a liquid changes to a gas. Many unknown liquids are often identified by measuring their freezing and boiling points. Measurements of freezing and boiling points are taken using the Celsius temperature scale (Figure 3). Celsius temperature has been accepted around the world and has everyday use in many countries. The freezing point of water on the Celsius scale is 0° C. The boiling point is 100° C. The thermometer has one hundred degrees of temperature between the freezing and boiling points, which is why the term centigrade is also used in referring to the Celsius scale. The Fahrenheit temperature scale is commonly used in many homes, but does not have the world-wide use that the Celsius scale has. The Fahrenheit scale is different in that water freezes at 32° and boils at 212°.

roperties of Matter ( 2 ) To understand fully the properties and nature of matter, we must look beyond the physical characteristics of matter. Here are your goals for this lesson: Explain what a chemical property is Identify the three states of matter Distinguish between crystalline and amorphous solids Vocabulary amorphous Shapeless; lacking complex organization. crystalline Mineral or element having geometric shapes as a result of orderly arrangement of its atomic structure. mineral An element or compound found in nature. pressure The force per unit of area. Vocab Arcade Chemical properties of a substance are characteristics that describe how a substance reacts with other substances. Chemical reactions depend on how different substances combine with each other. If an element will not combine with any other substance it is said to be inert. The souring of milk, the burning of a log, and the rusting of iron involve reactions of substances and changes in their chemical compositions. In rusting or burning, a substance combines with the oxygen in the air and causes change to take place. Burning involves a chemical process. The combining of a substance with oxygen is called oxidation. Rapid oxidation is burning. Rusting is caused by slow oxidation. Instant oxidation results in an explosion. Paper, wood, and cloth are three substances that burn and change composition. STATES OF MATTER Can you think of any matter that can occur in three different states? Before you try too hard to think of some strange type of matter, think of water. Water, a liquid, can freeze and change into ice. It can boil and change into steam (vapor). Ice, water, and vapor look very different; still, they are all water. At any given temperature, most substances exist in one of three states--solid, liquid, or gas. Does this remind you of someone who exists in three forms but is one person? Think of the triune God. God is manifested as the Father, the Son, and the Holy Spirit, yet all three persons are the same God. An interesting parallel, isn't it? In this section, you will study the three states of matter and their characteristics. Solids. If you were shown several containers of matter in all three forms, you would not have any trouble recognizing the solid matter. However, if the two solid objects you picked out were a pencil and a book and you were asked what made them both solids, what would you say? You might say that each object has a certain shape and that the shape will not change unless something is done to change it. As long as nothing is done to change the shape of the pencil or book, they will always take up a definite amount of space. In other words, all solids have a fixed shape and volume. There are two forms of solids: crystalline and amorphous. The form of a solid depends upon the arrangement of the atoms or molecules that make up the solid. A crystal is a form of solid that has a definite geometric shape. Every crystalline substance has a fixed internal geometric structure. Sometimes the orderly internal structure can be seen when the overall external appearance of the mineral forms a noticeable geometric shape. Many compounds are identified by their crystal form. The atoms, ions, and molecules of crystals are arranged in three-dimensional patterns. The surfaces of crystals are called faces. Crystals have their atoms, ions, or molecules arranged in some three-dimensional pattern. The surfaces of crystals are called faces. These faces follow a consistent pattern of forming angles with each other. For example, the faces of a salt crystal are at right angles (90°) to each other. If a crystal of a substance is split, each piece will have the same number of faces and the same angles. In other words, a large crystal of a substance has the same shape as a small crystal of the same substance. Crystals are formed in different ways. Salt crystals form when salt water is evaporated. Metal crystals are formed when molten (melted or liquid) metal is cooled to a solid. Amorphous, or noncrystalline, solids do not have an orderly internal arrangement of atoms or molecules. Glass has two properties of a solid (definite shape and volume), but it has no regular internal crystalline structure. Plastics, such as clear acrylics or polycarbonates, are also amorphous solids. Amorphous solids also chip or leave depressions when broken. Many such common substances as wax, fat, and plastic are classified as amorphous solids because they have no crystalline structure but will maintain a fixed shape at normal temperatures. When heat energy is applied to a solid, the solid melts to form a liquid, called the melting point. If heat energy is taken away from a liquid, a liquid will turn to a solid at its freezing point. Are these the same temperature for a given substance? Take ice as an example. If heat is added to ice, the ice will melt at 0 degrees Celsius. If heat is taken away from the ice, the ice will remain ice. The answer is yes, the melting point and the freezing point are the same temperature. The deciding factor is whether heat is being given off or applied to the substance. Liquids. Although a liquid maintains a fixed volume, it has mass and always takes the shape of its container. The molecules of liquids are not tightly bonded together; therefore, they are free to move. Because liquids have no definite form, the molecules tend to move toward the lowest point. It is often said that a liquid seeks its own level. Thus in a series of connected containers, the liquid will be at the same level in all containers (Figure 5). In most cases, the particles in a liquid are farther apart than the particles of a solid of the same substance. Thus, more empty space is between the liquid particles, allowing other particles to fill these spaces. You have probably noticed that many liquids easily mix with each other. One interesting feature of water is that, when it freezes, it expands. In other words, the volume of water increases when it becomes a solid. This is an exception to the rule however because in most liquids the volume will not increase in the solid form. For this reason, it can be dangerous to allow water to freeze in a closed glass container. When water freezes, it becomes less dense because its volume increases slightly due to expansion. It is very unusual for any substance to expand upon freezing or cooling; they usually contract. This unusual property of water permits ice to float on top of lakes, rivers, and oceans and prevents the underlying water from freezing. In this way, the ice acts as an insulator. Lucky for us that God made water with this wonderful property because it allows fish and plants to survive the winter freezes. Also, the salt content of ocean water greatly increases its resistance to freezing. At what point does a substance change from a liquid to a gas? Most commonly, it is called the liquid's boiling point, but again it depends on whether heat is being applied or given off. If heat is being given off, it can be called the substance's vapor point. Gases. Gases are different from solids and liquids in that they have no definite shape and no definite volume. An inflated balloon is different in shape from a deflated one. They are different because a gas blown into the balloon occupies space and takes the shape of the balloon. A gas always takes the shape of its container. Air, hydrogen, helium, oxygen, and carbon dioxide are gases. The particles (atoms or molecules) in gases are separated by large distances. Gases have very weak attractive forces meaning that the bonds between gases are weak. The key phrase in that statement is "bonds between gases." These types of bonds are called intermolecular bonds. "Inter" is a prefix that means between. These bonds should not be confused with intramolecular bonds. "Intra" means within. Intramolecular bonds are those that hold the molecule together within the molecule and in a gas they can be fairly strong. For example, in the air, molecules of oxygen flow around us and they don't attach themselves to one another, but rather float freely, because of the weak intermolecular bonds. But, the oxygen molecule by itself is two atoms of oxygen bonded to one another by an intramolecular bond and this bond is quite strong and needs energy added to break it. This type of bond will be discussed more fully in the lesson on molecules in this unit. Because gases are mostly empty space, the gas particles can be forced closer together. But they can also spread out and completely fill a large container. The volume of a gas is always determined by the volume of its container. Have you ever been in a small room and suddenly smelled perfume? The particles of perfume entered the air as a gas and will eventually fill the room. You can move to various positions in a room and, given enough time, smell the perfume wherever you are. Because gas molecules are constantly in motion and travel at high speeds, they collide with each other and the sides of their container. However, the gas particles do collide with each other and with the sides of their container. Collisions of gas particles in a container create pressure in the container. If the collisions are increased, the pressure is increased. When gas molecules are heated, they move faster and hit the walls of the container more often, increasing the pressure. When the number of molecules or particles of a gas increases, but the container stays the same, the pressure increases inside the container. Therefore, more than one event can increase or decrease gas pressure.

Acids A great variety of matter exists in the world, and it is necessary to have a method for classifying it. If we know something about the various properties of elements and compounds, we can classify them according to those properties and can more easily see the relationships. There are numerous compounds, but no two are exactly alike in all their properties. However, groups of compounds may have similar properties. Acids, for example, have similar properties. They have many uses and play an important part in our day-to-day living. In this section, you will study the properties of acids and some of the common acids and their uses. Here are your goals for this lesson: Describe properties common to all acids List some common acids Classify substances as weak or strong acids Define indicator and give an example Vocabulary acid A compound that yields hydrogen ions in water. base A compound that reacts with an acid to form a salt. corrode To eat away, break down, or become disordered. dehydrate To lose water. hydrogen A colorless gas made from the lightest element. hydronium A positive ion containing a hydrogen ion bonded to a water molecule. hydroxide A functional group made up of oxygen and hydrogen (-OH). indicator A substance used to show a change in chemical conditions. ion A charged atom or group of atoms. litmus A blue coloring matter obtained from certain plants. phenolphthalein A white powder used in testing acids and bases. Vocab Arcade PROPERTIES OF ACIDS Acids are important substances. They are found in nature, in industries, and in the home. Acids are easy to describe in terms of what they do. They are sour and they corrode most metals. For example, acetic acid found in vinegar causes the tart taste that gives flavor to salads and other foods. If a steel knife is left in vinegar, the knife will quickly corrode. All acids contain hydrogen. They should be handled very carefully because some acids can damage your skin, eyes, bones, or lungs. Common acids play an important part in daily life. Buttermilk contains lactic acid. We eat citric acid in lemons, oranges, and grapefruit. Hydrochloric acid in the stomach aids digestion. Most household bleaches are weak solutions of hypochlorous acid. Automobile batteries contain sulfuric acid. Three major commercial acids are sulfuric acid, nitric acid, and hydrochloric acid. Sulfuric acid (H2SO4) is a thick, oily liquid used to manufacture paints, plastics, and fertilizers. The solution in the storage of an automobile battery contains sulfuric acid. Sulfuric acid is also used to prepare other acids and to serve as a dehydrating agent. Dehydrate means to take water away. A wooden stick placed in sulfuric acid becomes charred as the acid removes water from it. Because it is a dehydrating agent, sulfuric acid can damage the skin. Nitric acid (HNO3) is oily, but it is not as thick as sulfuric acid. Like sulfuric acid, it is harmful to the skin. Nitric acid combines chemically with the protein in the skin to produce a yellow stain and indicates that better safety precautions should be taken while handling it. The yellow staining will gradually wear off. The difference between nitric acid and other acids is that nitric acid does not usually produce hydrogen when it reacts with metals. Nitrates are one product of the nitric acid-metal reaction. They are ingredients in fertilizers and explosives. Hydrochloric acid (HCl) is a strong acid made by dissolving the gas hydrogen chloride in water. The hydrogen chloride gas can be produced by heating sodium chloride (NaCl--table salt) with concentrated sulfuric acid. The gas is collected in distilled water where it forms hydrochloric acid. Observe the following list of acids and their formulas. Notice that hydrogen (H) is common to each one. Acetic acid CH3COOH Ascorbic acid C6H8O7 Carbonic acid H2CO3 Hydrochloric acid HCl Lactic acid C3H6O3 Nitric acid HNO3 Sulfuric acid H2SO4 Many other acids are also important. Formic acid was first found in ant bites and was isolated by distilling ants. Propionic acid is used to retard the spoilage of bread. THE HYDROGEN ION In an atom, tiny particles called electrons whirl around the nucleus. Each electron has one negative charge. You might recall that in an atom, the number of electrons equals the number of protons in the nucleus. This balance means that the atom as a whole is electrically neutral. That is, it is neither negative nor positive. The electrons alone are involved in chemical reactions. The hydrogen atom is the simplest of all the atoms. It has only one electron and one proton. If the hydrogen atom loses an electron, then only a proton, with a positive charge of electricity, remains. Since the hydrogen atom is no longer neutral it is called an ion, which by definition is an electrically charged atom. The hydrogen ion is indicated by the symbol H+. The H stands for hydrogen, and the plus sign means it has one positive charge. Now that we know what a hydrogen ion is, we can better understand the nature of an acid. An acid is any substance yielding a hydrogen ion (H+) in a water solution. Nearly one in every 500 million water molecules will ionize. A water molecule ionizes to form a hydrogen (H+) and hydroxide (OH-) ion. The equation for this ionization is: The hydrogen ion produced forms a bond with a water molecule. This particle is called a hydronium ion. Its formula is H3O+. Pure water contains an equal number of hydronium (H3O+) and hydroxide (OH-) ions. This ratio is changed if an acid or a base is added to the water. An acid added to the water would increase the hydronium ion concentration of water. pH OF ACIDS The degree to which a solution is acid is expressed in terms of its hydronium ion (H3O+) concentration. The symbol for hydronium ion concentration in a substance is pH. The pH scale goes from 0 to 14. Strong acids have a pH range of 0 to 3. Weak acids have a pH range from 3 to 7. The numeral 7 represents neutrality. That is, it is neither an acid nor a base. The following figure indicates the pH values of some common acids and foods. Indicators. How can we find out if a substance is an acid? Hydrogen ions can be detected in various ways. Litmus paper is a common acid-base indicator. Indicators are substances which react in a special way with hydrogen or other ions. Red cabbage and red onions contain colored substances that are also acid-base indicators. Litmus paper comes in red or blue. Blue litmus paper will turn red if it is placed in an acid solution. If the blue litmus paper does not change color, then the solution is either a base or neutral. Phenolphthalein is another commonly used indicator of acids and bases. Phenolphthalein is colorless in acid solution and turns pink when combine with a strong base like ammonia or milk of magnesia.

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Nuclear Changes A third type of change involves a change in the nucleus of the atom. This type of change is called a nuclear change. The sun is an example of nuclear change. Here are your goals for this lesson: Describe a nuclear change Differentiate between fission and fusion Vocabulary electron A small particle of an atom with a negative charge. fission The splitting that occurs when the nucleus of an atom absorbs a neutron. fusion The forming of larger atomic nuclei from smaller ones with a release of energy. nuclear Having to do with the nucleus of an atom. radioactive Giving off energy in the form of alpha particles, beta particles, or gamma rays. Vocab Arcade The sun is our primary source of energy. It is 93 million miles away, yet a small amount of its total heat energy provides the earth with a tremendous amount of energy. Scientists know that the amount of heat given off by the sun can not result simply burning fuel. The kind of change taking place in the sun is neither physical nor chemical; it is nuclear. In this section you will study two different nuclear changes and the particles they produce. Nuclear fission. Atoms have a tremendous amount of energy locked within their nuclei. Nuclear energy must be released to be used. Nuclear fission is one way nuclear energy is released. Fission means to divide. In nuclear fission, the nucleus of certain elements splits into two nuclei. Nuclear fission is nuclear change. When a uranium 235 atom is bombarded by neutrons, it splits into two nuclei. The daughter nuclei are almost equal in size. Uranium fission results in a chain reaction. First, a uranium nucleus is split by a neutron. The splitting releases two other neutrons. The two neutrons are captured by two more nuclei, which split. The fission of nuclei and the emission of neutrons continue throughout the sample if enough uranium is present. A neutron that travels more than ten centimeters without hitting a nucleus slows down too much to split another nucleus. During fission, an extremely small mass is changed to energy. The energy is given off as gamma radiation. The term radiation is applied to energy or to high-speed particles given off in a nuclear reaction. Matter that gives off atomic particles or energy is radioactive. Early in their study, scientists thought that all radiation was energy, and so named the three types of radiation alpha rays, beta rays, and gamma rays. Research has revealed that alpha rays are really fast moving helium nuclei, each made of two protons and two neutrons. Beta rays are electrons emitted from atomic nuclei. Gamma rays are a very high energy form of light waves. The three forms of radiation range from high penetration gamma rays to relatively low energy alpha particles. Research labs or containers which use radioactive materials are labeled with a hazardous warning symbol like the one at right. Exposure to radioactive elements can be fatal. A Geiger counter is used to detect radiation. Nuclear fusion. Nuclear fusion is the opposite of nuclear fission. Fusion means to fuse or join together. In nuclear fusion, two or more atomic nuclei unite to form a single, heavier nucleus. This is the type of reaction that occurs in the sun. Elements with small masses join together to form elements with larger masses. Hydrogen, deuterium, and tritium are raw materials commonly used in nuclear fusion. Temperatures in the millions of degrees must be reached for nuclear fusion to occur. Nuclear fusion is also called a thermonuclear reaction. Thermo- means heat. At the tremendous temperatures of thermonuclear reactions, atoms lose their electrons and no longer exist as atoms. This state of matter is called the plasma state. It consists of ions and free electrons. The plasma phase is different from solid, liquid, or gas states, and is often called the "fourth state of matter". At nuclear fusion temperatures, matter becomes plasma and charged nuclei are formed, which can be squeezed together and fused. The sun sets the right conditions for nuclear fusion to occur. The sun has an internal temperature of approximately twenty-seven million degrees Fahrenheit. Through a complex series of nuclear changes, four hydrogen nuclei are fused into one helium nucleus. The sun is constantly losing hydrogen and gaining helium through nuclear fusion. The helium atom has a mass almost one percent less than the mass of the original four hydrogen atoms. This mass defect (deficiency) is equivalent to the energy produced. Nuclear fusion also occurs in the explosion of a hydrogen bomb. The reactions in a hydrogen bomb are similar to the reactions in the sun. The temperature inside an exploding hydrogen bomb is about 10 million degrees Celsius. An atomic bomb is used as a fuse to produce a temperature high enough to start nuclear fusion for a hydrogen bomb.

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Elements Scientists have discovered a lot about God's universe and the matter that forms it. All matter can be divided into three groups: elements, compounds, and mixtures. What you learn in this section will help you classify particular items, such as sugar or iron, as elements, compounds, or mixtures. Here are your goals for this lesson: Define element Examine how the periodic table is organized Calculate the number of electrons, protons, and neutrons in a given atom Vocabulary mixture A combination of two or more components that retain their own properties. periodic Occurring at regular intervals. Vocab Arcade ELEMENTS Defining elements. Elements are substances composed of only one kind of atom. Each element's atoms are distinct from those of other elements. Elements are sometimes called the building blocks of the universe. There are over one hundred elements. Many substances we use regularly are elements. These elements include iron, tin, oxygen, and aluminum. Gold, silver, and mercury are also elements. The elements carbon, hydrogen, oxygen, and nitrogen are plentiful in living things. Food, wood, paper, and most fuels are rich in carbon and hydrogen. Your body is made of carbon, hydrogen, oxygen, nitrogen, sulfur, phosphorus, and calcium with traces of several other elements. Elements exist as solids, liquids, and gases. Iron and lead are examples of elements that are solids. Mercury, the silver-colored metal often used in thermometers, is a liquid at room temperature. The air you breathe is made up of several elements which are gases. Classifying elements. Scientists have found that elements differ from one another. Oxygen is different from lead. Iron is different from sodium. They not only look different, but they react differently with other elements. Although every element has special features, scientists have found that certain elements have some things in common. As the atomic number of elements increases, certain chemical properties reappear periodically. This discovery resulted in a classification system called the Periodic Table of the Elements. There are 118 identified elements and 116 confirmed elements. An element needs to be confirmed by two different labs before the International Union of Pure and Applied Chemistry (IUPAC) considers adding it officially to the periodic table. Ninety eight of these elements occur naturally. Some of the elements were first artifically synthesized in a lab but later were discovered to have been found in very small amounts in samples of uranium-rich deposits. The rest are synthetic (made in a laboratory) and radioactive. The first synthetic element, called Technetium, was discovered in 1937. The Periodic Table is an orderly grouping chemical elements known to scientists. This table includes the name of each element, its symbol, atomic mass (weight), and electron distribution. The first letter of each chemical symbol is capitalized. Study the Periodic Table of the Elements in the resource center. Notice that the elements are arranged in both horizontal (sideways) rows and also in vertical (up and down) columns. The horizontal rows are called periods. Elements in the same period all have the same number of electron shells. The vertical columns divide the elements into groups. All the elements of the same group have similar chemical properties. Some groups have special names. The elements in group 18 are called noble gases. The elements in group 1, except for hydrogen, are called alkali metals. Click here to open a copy of the Periodic Table that can be printed out. You can learn to read the table by looking at an entry for one of the elements. Study the entry for calcium below. The atomic number is 20. This means that the calcium atom has 20 protons in its nucleus. The atomic mass (sometimes referred to as weight) is 40.08 and the electron distribution is two, eight, eight, two. With this information, you could diagram an atom of calcium. An example diagram is shown below. Notice that there are four shells around the nucleus. Each shell is identified with a number, n = 1, 2, 3, and 4. The n = 1 shell has two electrons, the n = 2 and n = 3 shells each have eight electrons, and the n = 4 shell has two electrons. Many elements of the Periodic Table have the electron distribution number listed for each element. If four numerals are listed for an element, you can assume that the element has shells n = 1, 2, 3, and 4. The sequence of numerals tells you the total number of electrons in each shell. The outer or highest shell, n = 4 in the case of calcium, represents the valence electrons. Valence electrons are those electrons that give an element its chemical properties or reactivity. In an atom, nearly all of the mass is in the nucleus. Electrons have almost no mass. The particles in the nucleus which give it its mass are the protons and neutrons. Since the atomic number of an element tells you the total number of protons in each atom of a specific element, the atomic mass of an atom is obtained by adding neutrons. For example, the Periodic Table gives the atomic mass of calcium (Ca) as 40.08. To figure out the number of neutrons, this number needs to be rounded to the nearest whole number, therefore calcium's rounded mass is 40. To get a total of 40 particles in the center, you need 20 neutrons (n) plus 20 protons (p) to have the necessary 40 particles in the nucleus. A simple formula for this is as follows: rounded atomic mass - atomic number = # of neutrons. Consider the element Beryllium. It has an atomic number of 4. This tells us that there are four protons in the nucleus. Since the atomic mass is 9.013 it is rounded to 9 and the difference between the rounded atomic mass and the atomic number is the number of neutrons in Beryllium. Therefore, five neutrons are in the nucleus. The number of electrons in each shell is given to the upper left. The number of valence electrons is 2 in n = 2.

Compounds A compound is a chemical combination of two or more different elements. As of 2011, there are 118 identified elements and as of 2013, 116 confirmed elements. An element needs to be confirmed by two different labs before the International Union of Pure and Applied Chemistry (IUPAC) considers adding it officially to the periodic table. There are several thousand known compounds. Here are your goals for this lesson: Explain what a compound is and how it forms Analyze the use of chemical formulas to name a compound Interpret a chemical formula Definition. A compound is made up of two or more different elements. The atoms within each molecule of a compound are chemically joined together, not just mixed. The elements are held together or bonded in a way that makes it difficult to separate them. Water (H2O) is an example of a compound. It is made of two different elements, hydrogen and oxygen. Carbon dioxide, salt, sugar, and ammonia are other examples of compounds. Each one contains two or more elements chemically joined. Figure 18 lists a few compounds and their elements. Notice that the strength of the bonds between molecules determines whether the compound is classified as a solid, liquid, or gas. Formulas. Just as a chemical symbol is used to name an element, a chemical formula is used to name a compound. A compound contains two or more elements. A chemical formula contains the symbols for the elements in the compound it names. For example, water contains hydrogen and oxygen. The formula for water is H2O. O2 is the formula for oxygen gas and N2 is the formula for nitrogen gas. The subscript 2 in each of these formulas represents the number of atoms of the element it follows. An element without a subscript means it has only one atom in that compound. For example, in carbon dioxide (CO2), the 2 shows two atoms of oxygen for each atom of carbon. The formula for table sugar (sucrose) is C12H24O12. In this case the ratio of carbon, hydrogen, and oxygen is 12 : 24 : 12. There are 12 atoms of carbon, 24 atoms of hydrogen, and 12 atoms of oxygen per molecule. Figure 19 lists several common compounds and their formulas. It is possible for two compounds to contain the same elements and have similar names. However, they will have different properties. For example, carbon dioxide (CO2) and carbon monoxide (CO) are two different compounds. They contain the same elements in different ratios. These two compounds are very different. Carbon dioxide (CO2) is used to put out fires and is exhaled by humans and other mammals. Carbon monoxide (CO) burns easily and is poisonous when inhaled. You can see how important subscripts are when using formulas to represent compounds.

Modern Technology Modern technology. During the twentieth century, technology has created new and amazing products at a very rapid rate. Previously, the development of technology was comparatively slow. Later we will discuss where this rapid advance may be taking us. However, in this section we will deal with where we are at present. One of the most spectacular fields of technology today is space exploration. Beginning several years ago with the tiny Russian satellite; Sputnik, rockets, satellites, and space shuttles have been developed. Now, people can either visit or view Earth's closest neighbors. Satellites orbit the earth in increasing numbers. Space stations have been established and maintained to give us more information about outer space and about our earth. These advances in rocketry and space travel have produced major developments in the field of communication. In the late 1800's, Alexander Graham Bell invented the telephone. Now, the telephone is only a small part of a vast network of communication. Telephones, cell phones, fax machines, satellites, cables, fiber optics, and the internet connect all points of the earth almost instantly. Without these complex forms of communication, society as we know it could not exist. It would be slower-paced and more restful perhaps, but it would be neither as stimulating nor as comfortable. The advancements of technology bring both blessings and problems. Better living conditions and nutrition, as well as improved medical technology, are lengthening the life span of human beings. Various mechanical devices enable people with serious health problems to continue living when prior to modern technology they would have died. The ventilator and the oxygen tent make breathing easier and even possible for those with lung problems. Other machines keep hearts beating or body systems functioning. Machines that sustain life are joined by medicines which protect life. Antibiotics, pain relievers, medications for cardiovascular health, and a host of others serve to protect and prolong human life.

Limitations of Science and Technology Our understanding of the universe is based on what we can observe and measure. This leads to obvious limitations. If we cannot observe something, we cannot measure it. Therefore, as we develop greater capabilities to observe and measure, we will be able to get a more accurate picture of the existing universe. Here are your goals for this lesson: Examine the need for a moral guide, the Bible, as scientific knowledge increases Explore the goals today for technology in life science, physical science, and earth science List some of the difficulties and problems that technology is faced with in today's society Vocabulary biodegradable Capable of being broken down by bacterial action. cloning Process of reproducing many identical organisms from pre-existing genes. DNA Twisted strand of molecules in a cell nucleus containing genes and hereditary information. microbiology Study of the cellular structure of organisms and microorganisms. pollution The contamination of the earth. Vocab Arcade People's inherent challenge is applying what he or she knows. As the body of scientific knowledge continues to grow, this new knowledge can be used for either constructive or destructive purposes. In recent history we have seen examples of both, with the development of the atomic bomb on one hand, and advancements in medicine on the other hand. To make these decisions, people need a moral guide - the Bible. In it, people can know with certainty the mind of God on these matters. This is the standard we must adhere to in considering controversial matters. PROJECTIONS FOR SCIENCE AND TECHNOLOGY Technology and science are working to improve living conditions. Since we know the sorts of things they are doing today, we can estimate what they will accomplish tomorrow. Technology holds hope for the future in three fields: life science, physical science, and earth science. Goals in life science. Both pure scientists and technologists are working to solve the many problems in the world. In the field of life science, exciting discoveries are being made each day. One important goal is a cure for cancer. Each year claims are made for the ultimate cure; not one of them can surpass extensive testing. Advances in the science of microbiology have greatly increased our understanding of the basic life processes of the living cell and the mechanism of reproduction. The inheritance of physical characteristics through information stored chemically in the genes is an area of science and applied technology which has "exploded" in the last several decades. As new instruments allow scientists to probe deeper into the structure of the cell, it is becoming more obvious that life could not have originated solely through accidental natural chemical processes. The extreme complexity of life is more and more evident as research continues. An area of research stirring much debate is the technology of cloning. This area of experimentation requires great godly wisdom because it deals with the reproduction of microbes, plants, living animals, and possibly human beings. This process may have some beneficial uses, but it may also be misused or abused. Cloning involves the reproduction of identical multiples of organisms from pre-existing genes. Cloning is not creation! However, it now appears that the cloning techniques being developed can duplicate a created organism to some extent. In fact, scientists in Scotland cloned a live sheep, which stirred much scientific interest and brought up serious ethical questions. This type of "reproduction" is done by biological manipulation of the DNA (combination of genes) which is obtained from the cell nucleus of a pre-existing organism. Life science, more specifically microbiology, is open for any Christian to pursue as a career. This field of research certainly needs many Christian scientists to help direct it according to God's will. Goals in physical science. One of the major goals in physical science is space exploration. New developments in exploration and supporting equipment are essential to discover what lies beyond what we have been able to observe. Physical scientists and technologists conduct extensive research in national defense. A variety of guns, explosive devices, missiles, and missile detectors enhance our defensive arsenals. Goals in earth science. In the earth sciences, some major concerns are pollution, mineral location, and diminishing fuel supplies. Industries are employing pollution-control devices. International organizations attempt to clean polluted areas and to educate the public in ecology and conservation. Oil companies probe for new supplies of petroleum and natural gas. They also research new and more efficient means of using these fossil fuels. While the future seems to hold great promise in these scientific fields, a word of caution is appropriate. Science and technology are limited in what they can accomplish. CONFLICTS WITH SOCIETY Technology's purpose is to solve problems and meet needs. Unfortunately, a solution to one problem will sometimes cause another problem. Society's needs. Today, people still have the basic needs of food, warmth, clothing, and shelter. In ancient societies these needs were met in only the most basic ways. As societies have grown more complex, their needs have changed as well. This saying is true: "The more you have, the more you want." People today demand specialized solutions to their needs and wants. No longer will a tent, a roast lamb, a woolen caftan, a camel, and a piece of parchment suffice. Technology's solutions. As society's demands have grown, so technicians have striven to fulfill those demands. As life begins to move faster and faster, quick, easy-to-prepare food, easy-to-maintain clothing, and efficient shelter have become important items in our lives. Technology has worked to meet these demands by developing foods that are easier to prepare, and clothing that is easier to care for. Apartment living is prevalent in all large cities. Air conditioning and heating, built-in appliances, and other conveniences make an apartment a suitable solution for the housing needs of many people. Homes are roomier, cleaner, more comfortable, centrally heated, and air-conditioned. People today would cringe at the idea of living in the tiny wooden or adobe homes people once occupied. People in today's world are interested in going places. They move rapidly from place to place. Technology has kept up with this desire by producing automobiles, trucks, and motorcycles in great variety. The needs of society are constantly being met by technology in new and exciting ways. Society's problems. As people live together, certain difficulties are bound to arise. When the population grows, these problems happen faster and affect a larger number of people. Because of a rapidly expanding global population, food has become scarce and even unobtainable in some parts of the world. Famines do not result from the failure of technology, however. God has provided an abundance of land on this earth and the technology to produce sufficient food for all nations. People's general unwillingness to share God's provision is the primary factor which causes nutritional, medical, and other related problems. God created the earth to provide sufficient resources for mankind. Did he make a mistake by forgetting to consider the world's growing population? Does God make mistakes? The answer to both of these questions is no. Another problem is the fuel shortage. Since human beings require protection from the elements, fossil fuels such as natural gas, petroleum, and coal are being rapidly used. Many scientists disagree on how long the fossil fuels will last. At the time it was being developed, atomic energy seemed to be an adequate substitute for fossil fuel energy. The use of atomic energy has now been greatly reduced, however, because science has not solved the problem of safely disposing of the nuclear wastes. New sources of energy need to be developed. Solar energy is one possible energy source that has been explored. Some large buildings and some private homes utilize solar energy. It is a clean, safe source of heat and power. We have technology to thank for making practical the use of the sun's energy. Transportation is still another problem area in today's society. Most families own at least one automobile, and many people commute to work in large cities. Congestion on the highways is severe in urban areas. The challenge is to move the mass of humanity between home and job with a minimum of trouble, energy use, and pollution. Other problems could be cited, but these should be sufficient to indicate the types of difficulties technology is faced with in a fast-paced society. Technology's problems. As technology seeks to supply the needs and solve the problems of society, difficulties inevitably arise. In solving food shortages, technology has created a new kind of problem. Some artificial foods have been identified as having a possible link to cancer. Convenience foods, which are often preferred to less-processed foods, are often poor in nutrition. Technology has produced a variety of chemicals that are used on plants and animals. For example, chickens are fed supplements that cause them to grow plump, and vegetables are sprayed with chemicals to protect them from insects and fungus. However, these supplements and insecticides can cause sickness and injury to human beings who ingest them. Chemicals and artificial foods definitely have a place in our world, but caution in their use is essential. Technology is doing society a great service in the field of energy. Since all fossil sources of energy are limited, technology is working on alternate sources of energy. Atomic power is one alternate source of energy, but the consequences of a malfunction or breakdown in a nuclear power plant can be severe. Many people strongly object to having nuclear power plants or storage areas in their communities because of the danger involved. Technologists are always striving, however, to design safer power plants. Today, contamination from radioactive leakage is rare. One problem caused by technology is pollution. Air, water, land, sound--all are polluted to some degree. Wastes necessitated by industry pour into the earth's air and water. All kinds of packaging, from cereal boxes to aluminum cans, litter the roads. Pollution has contaminated our streams, making them both unsightly and unfit from which to drink. Automobiles and other vehicles pollute the air with exhaust fumes. None of these problems can be blamed entirely on technology and industry. People are also to blame. Rather than take reasonable precautions, many people misuse their prosperity. They are inconsiderate of God's creation and their fellow creatures. Like the steward in Luke 16:2, we will be held accountable for our part in taking care of what God has given us. Although technology and industry have caused many problems, they are constantly searching for ways to overcome these difficulties. In many areas, industries are seeking ways to cut down on pollution. Automobiles are equipped with exhaust-control devices, bottling plants pay to have aluminum cans returned for recycling, paper manufacturers use recycled paper, food manufacturers use biodegradable containers, and soap and detergent manufacturers restrict the amount of phosphate in their products.