Science Praxis: Matter

Ionic is taking. Covalent/molecular is sharing.

..

When a substance undergoes a _____ change, one or more new substances are formed. A chemical B ecological C physical D natural

A. A chemical change results in the production of one or more new substances that have different properties from the original substance. The new substance is chemically different from the original (Ex. burning wood is a chemical change because it changes the wood into ashes.)

Which of the following is a chemical reaction? A digesting food B smashing a rock into pieces C water boiling D mixing oil and vinegar in a table dressing

A. Digestion changes the chemical compound of the food and is, therefore, a chemical reaction.

When Terry put a marble in a graduated cylinder of water measuring 47 mL, the water level increased to 51 mL. Which principle describes the increase in water volume? A. conservation of matter B. density C. conservation of energy D. buoyancy

A. Matter takes up space, or has volume, and has mass. When the marble is dropped into the graduated cylinder of water, the new reading on the graduated cylinder is the sum of the volume of the water and the volume of the marble.

Which of the following statements is true regarding protons and atoms? A In an atom, the protons are located inside the nucleus. B In an atom, the protons can be inside or outside the nucleus. C In an atom the protons are located inside the nucleus, but they leave the atom when they collide with electrons. D In an atom, the protons orbit outside of the nucleus of the atom.

A. Protons in an atom are located inside the nucleus, as are the neutrons.

Which of the following is the best example of a homogeneous mixture? A a bag of rice B trash in a kitchen wastebasket C a bowl of Raisin Bran cereal and milk D Caesar salad

A. Rice in the bag is uniformly mixed; therefore, it is a homogeneous mixture.

Which of the following is a base? A dish soap B Italian salad dressing C an orange D pure water

A. Soaps are bases.

One of the most commonly used examples of a solution is: A the atmosphere. B a peanut butter and jelly sandwich. C a bowl of cereal. D the rock layers comprising the fossil record.

A. The atmosphere is one of the most commonly used examples of a solution because it is something we see every day of our lives and is a homogeneous mixture that contains a large number of different gases which we are unable to visibly distinguish.

What happens to a liquid when its temperature cools to its melting point temperature? A. It begins to solidify. B. It begins to become a gas. C. It begins to evaporate. D. It begins to melt.

A. The melting point is the temperature at which solids begin to melt into liquids and liquids begin to condense into solids. The melting point is also called the freezing point.

All atoms of a single element have the same number of: A protons. B. electrons. C. neutrons. D. all of the above.

A. The number of protons in the nucleus characterizes the type of atom, i.e. all carbon atoms have 6 protons and all oxygen atoms have 8 protons.

What are valence electrons in an atom? A electrons in the outermost orbit of an atom in the ground state B electrons in the innermost orbit of an atom in the ground state C electrons that are bound so tightly to the nucleus of an atom that they will never escape D electrons that move freely in a material and are not bound to any individual atom

A. Valence electrons are the outermost electrons in an atom that is in the ground state. The number of valence electrons in an atom determine its chemical properties.

Which of the following is an example of a molecule? A H₂O (water) B NaCl (salt) C N (nitrogen) D None of the above are molecules.

A. Water, H₂O is a molecule. It is formed from 3 atoms held together by molecular bonds.

A liquid is heated to its boiling point temperature. If further heat is added to the liquid it will: A stay at its boiling point temperature until all of the liquid has evaporated. B decrease in temperature until all of the liquid has evaporated. C increase in temperature but remain a liquid. D increase in temperature as the liquid evaporates.

A. When heat is added to a liquid at its boiling point temperature, the heat energy breaks the bonds holding the atoms together as a liquid rather than raising the temperature of the liquid. The temperature remains at the boiling point temperature until all of the liquid has evaporated.

Is matter conserved during a chemical change? A Yes, the atoms are rearranged during a chemical change, but the same number and types of atoms are still present. B No, since atoms are rearranged during a chemical change, the number and types of atoms also change. C No, because less matter is present after atoms combine by forming chemical bonds. D Yes, because the same total number of atoms are exist before and after the reaction, only the types of atoms have changed.

A. Yes, matter is conserved during a chemical change. The same number and types of atoms are still present before and after a chemical reaction, but they will be combined differently than before the reaction.

..... have a very small, dense nucleus, or central core, made of positively charged protons and neutral neutrons, and a much larger cloud of negatively charged electrons that orbit the nucleus.

Atoms

....... are the smallest particle of an element.

Atoms

Which of the following characteristics always describes a solid? Select all answers that apply. A always clear B rigid C definite shape D fixed volume

B, C, D

Which of the following characteristics always describes a gas? Select all answers that apply. A. rigid B. changing volume C. definite shape D. can be compressed (squashed)

B, D

Which of the following particles resides in the nucleus of an atom? Select all answers that apply. A neutrino B proton C electron D neutron

B, D.

Which of the following object best conducts electricity? A oxygen gas B copper C wood D pure water

B. A good electrical conductor has relatively free electrons that can move through a material. Metals, notably copper, are a good conductors because they allow electrons to move along the wire easily.

A material in which electrons move freely is called a: A resistor. B conductor. C insulator. D semiconductor.

B. A material in which electrons are free to flow is a conductor. Conductors such as copper wire are often used in circuits so electrons can flow freely between components in a circuit.

Nitrogen gas, N2, is classified as which of the following? A. a salt B. an element C. a compound D. a solvent

B. A molecule is an element if it consists only of elements with the same number of protons.

Which type of change has taken place if a substance's shape, appearance, color and/or volume has changed? A negative B physical C electrical D chemical

B. A physical change has occurred if a substance's shape, appearance, color and/or volume has changed.

When a substance changes state, it undergoes a ____ change. A chemical B physical C ecological D natural

B. A physical change physically alters a substance, but its chemical composition remains the same. A change of state, such as freezing water to form ice, changes the physical structure of the water, but does not change water into a different substance.

A water molecule (H₂O) can break into a positively charged H+ ion and a negatively charged OH- ion. Acids have an excess of which kind of particle? A H₂O B H+ C ions, both H+ and OH- D OH-

B. Acids are solutions with an excess of H+ ions.

A water molecule (H₂O) can break into a positively charged H+ ion and a negatively charged OH- ion. Bases have an excess of which kind of particle? A H₂O B OH- C H+ D ions, both H+ and OH-

B. Bases are solutions with an excess of OH- ions.

Which of the following describes a compound? A Atoms of a single element joined together by ionic or molecular bonds. B Groups of two or more different elements held together by ionic or molecular bonds. C Atoms that are mixed together without a chemical bond. D Electrically neutral particles made of two or more atoms joined together by molecular bonds.

B. Compounds form from two or more different elements, and can have either ionic or molecular bonds.

Which statement best describes why a cork floats in water? A Electrons in the water repel electrons in the cork. B The density of cork is less than the density of water. C Convection currents in water move the cork upward. D The buoyant force is an in

B. Corks float because they are less dense than water. For example, 100 mL of water has more mass than 100 mL of cork. The upward buoyant force on the cork equals the weight of the water that is displaced by the cork. Since the density of water is greater than the density of cork, the cork experiences a large buoyant force and is pushed upward by the water.

Which of the following statements is true regarding electrons? A Electrons are positively charged particles that orbit around the outside of the nucleus of the atom. B Electrons are negatively charged particles that orbit around the outside of the nucleus of the atom. C Electrons are negatively charged particles located inside and outside of the nucleus of the atom. D Electrons are negatively charged particles located inside the nucleus of the atom.

B. Electrons are negatively charged particles that orbit around the outside of the nucleus of the atom.

Which of the following particles can be found orbiting outside the nucleus of an atom? A neutrons B. electrons C. photons D. protons

B. Electrons have a negative charge and orbit outside the nucleus of an atom.

Each element is always identified on the periodic table by: A its name, spelled out in each square of the table. B a symbol representing its name and by its atomic number. C its mass number and its electron configuration number. D its atomic number and its mass number.

B. On the periodic table, each element is represented by a symbol that represents its name, and its atomic number, which equals the number of protons in the nucleus of that atom. For example, Fluorine is represented by the symbol F and has an atomic number of 9.

Which subatomic particles orbit around the nucleus of the atom? A neutrons B electrons C protons D subtrons

B. The electrons orbit around the nucleus of the atom.

Michelle pours lemonade powder into a cup of ice and water. She stirs it with a spoon to mix up the powder more quickly. What is the solvent? A the lemonade powder B the liquid water C the spoon D the frozen ice

B. The material that the object is dissolved within is the solvent. The lemonade powder is dissolved into the water, so the water is the solvent.

When oxygen and hydrogen combine to form water, what type of change has occurred? A Physical B Chemical C Electrical D Nuclear

B. When oxygen and hydrogen combine to form water, a chemical change has occurred. The oxygen and hydrogen have formed a new substance.

A solution of 4 on the pH scale is: A neutral. B an acid. C positive. D a base.

B. When the pH is less than 7, the solution is an acid.

Which of these is considered to be a good conductor? A glass B plastic C metal D wood

C

Which of the following characteristics always describes a liquid? Select all answers that apply. A always clear B can be compressed C has a fixed volume D has a non-fixed shape

C D

A frozen popsicle was left in the sun and melted. Which statement is true regarding the physical properties of the popsicle after it melted? A Its molecules were less energetic after it melted. B Its chemical composition had changed. C It experienced a phase change. D The number of molecules had changed

C.

A solution of 9 on the pH scale is: A. an acid. B. negative. C. a base. D. neutral.

C.

Elements in the right-most column of the periodic table, such as neon and argon, are very chemically unreactive. Which chemical property does this statement describe? A. toxicity B. flammability C. chemical stability D. radioactivity

C. A chemically unreactive element is chemically stable. It is unlikely to undergo a chemical reaction.

Which of the following is an example of a physical change? A photosynthesis B mixing vinegar and baking soda C water boiling D lighting a candle

C. A physical change takes place when water boils. The process does not form a new substance.

Which of the following is an example of a chemical change? A boiling water B chopping wood C baking a cake D melting ice cream

C. Baking a cake is an example of a chemical change. Chemical changes occur when substances combine to form new ones or substances decompose into different substances. Signs of chemical changes include odor, temperature change, precipitate formation, production of gas bubbles, and changes in color.

Condensation occurs when: A. a liquid is heated to its boiling point temperature. B. a solid is heated to its melting point temperature. C. a gas cools to its boiling point temperature. D. a liquid is cooled to its melting point temperatur

C. Condensation is the phase change from a gas to a liquid. This occurs at the boiling point temperature of the material, which is also called the condensation point.

The first several elements are grouped into eight columns in the periodic table labeled columns I through VIII. Elements in which columns of the periodic table tend to form ionic bonds with each other? A elements in columns III and IV B elements in columns I and VIII C elements in columns I and VII D elements in columns III and V

C. Elements in column I have one valence electron, which is easily donated to elements in column VII, with seven valence electrons. Elements in columns I and VII generally form ionic bonds.

Which of the following describes the process of sublimation? A Pure water breaks into charged ions of hydrogen and hydroxide. B A pure liquid changes directly into a gas. C A pure solid changes directly into a gas. D The atoms in a material combine with pure oxyg

C. In sublimation a pure solid experiences a phase transition directly to a gas.

Bleach, which has a pH of about 12, can be classified as which of the following? A weak base B weak acid C strong base D strong acid

C. Strong bases have a pH value close to 14. Bleach, with a pH of about 12, is a strong base.

A frozen popsicle was left in the sun and melted. Which statement is true? A The temperature of the popsicle decreased. B The volume of the popsicle increased. C The molecules started to move more and became more loosely packed. D Energy was removed from the popsicle.

C. The molecules started to move more and became more loosely packed.

The periodic table is a chart of: A the time of one wave cycle, arranged from shortest to longest. B molecules, arranged from the least to the most complex. C the elements, arranged from least to greatest atomic number. D the tides, arranged by date and time.

C. The periodic table is a table of the elements, arranged from the least to the greatest atomic number. The atomic number of an element equals the number of protons it has in the nucleus of each atom.

Which atomic particles are located inside the nucleus? A electrons B subtrons C protons D magnetrons

C. The protons are located inside the nucleus of an atom.

Which of the following is an example of a compound? A Fe (iron) B O₂ (oxygen gas) C H₂O (water) D N₂ (nitrogen gas)

C. Water, H₂O, is a compound (as well as a molecule). Compounds form from 2 or more different atoms held together by ionic or molecular bonds.

....... are groups of two or more different elements held together by ionic or molecular bonds. For example, water (H2O) is a molecule and a compound. It is electrically neutral and its elements are bound by molecular bonds, so it is a molecule. It is composed of two different elements, so it is a compound.

Compounds

Which of the following is an example of an element? A NaCl (salt) B N₂ (nitrogen gas) C H₂O (water) D C (carbon)

D

A solution of 7 on the pH scale is: A. an acid. B. a base. C. positive. D. neutral.

D.

A water molecule (H₂O) can break into a positively charged H+ ion and a negatively charged OH- ion. A neutral solution must have: A equal numbers of H₂O molecules and OH- ions. B more H+ ions than OH- ions. C more OH- ions than H+ ions. D equal numbers of H+ and OH- ions.

D. A neutral solution is neither an acid nor a base and has equal numbers of H+ and OH- ions.

Which of the following would be considered a phase change? A A change in temperature due to a chemical reaction between two substances. B A change in the chemical properties of a substance when heat is added. C A change in color as a material is heated. D A change in state from a solid to a liquid.

D. A phase change is a change in the state of matter, generally caused by heating the material. The change of solids to liquids and liquids to gases when heated, and from gases to liquids and liquids to solids when cooled, are phase changes.

Which of the following steps in making coffee involves a chemical change? A grinding the coffee beans B heating the water with a hot plate C the water boiling in the kettle D None of these.

D. All of the choices provided are physical, not chemical, changes.

Students were asked to observe chemical reactions taking place and then record their observations in a data table. Which of the following observations would indicate a chemical reaction has most likely occurred? A the production of bubbles B flames C a change in color D Any of the above could indicate a chemical reaction has taken place.

D. All of these observations could indicate that a chemical reaction has taken place.

Which are the smallest particles of an element? A. protons B. compounds C. molecules D. atoms

D. Atoms are the smallest particles of an element. If broken into protons, neutrons, and electrons, the element no longer exists.

In the periodic table, atoms with the same number of valence electrons are grouped: A in the bottom half of the chart. B in the same row. C in the top half of the chart. D in the same column.

D. Atoms with the same number of valence electron are grouped by column in the periodic table. For example, each type of element in the first (leftmost) column of the chart has 1 valence electron.

Which of the following is a chemical property? A freezing point B hardness C density D flammability

D. Chemical properties involve chemical reactions in which the atoms and molecules in a substances interact to form a new substance. When something burns, a chemical reaction occurs between the substance and oxygen. For example, burning wood involves a chemical reaction. The substances that interact are wood and oxygen, one of the new substances is ash.

Boiling point temperature is NOT considered a chemical property of a material. Why is the boiling point temperature NOT classified as a chemical property? A A boiling point temperature does not indicate flammability. B The molecules in a gas are generally farther apart than the molecules in a liquid. C The procedure of turning a liquid into a gas is reversible. D When a substance evaporates, it does not become a new substance.

D. Chemical properties only describes situations in which the atoms and molecules in a substances interact to form a new substance.

Which of the following best describes an ionic bond? A bonds that form by physical means in a mixture B bonds that form when electrons are shared between atoms C bonds that form when iron atoms combine with arsenic D bonds that form when electrons are removed from one atom and given to an atom of another element

D. Ionic bonds are bonds that form between two oppositely charged atoms after one of the atoms has donated electrons to the other.

Which of the following is an example of a chemical change? A shattering glass B sanding wood C ice cream melting D mixing baking soda and vinegar

D. Mixing baking soda and vinegar is a chemical change. A new substance, carbon dioxide, forms in the reaction.

Which of the following describes a molecule? A A mixture of two or more atoms, with no chemical bond between them. B Groups of two or more different elements joined by ionic or molecular bonds. C Atoms of a single element joined together by ionic bonds. D Electrically neutral particles of two or more atoms joined by molecular bonds.

D. Molecules are electrically neutral particles made of 2 or more atoms (not necessarily 2 different elements) joined together by a molecular bond.

Which of the following is the best example of a heterogeneous mixture? A Table salt in the salt shaker. B Apple cider in a big, tall, glass. C Fine potting soil around a potted plant. D Layered gravel at the bottom of an aquarium.

D. The layered gravel is not uniformly mixed, therefore, it is a heterogeneous mixture.

Moshi put on a magic show for his classmates. He made a metal car move by waving a paper wand behind it. Which of these is probably the secret to his successful magic trick? A The wand increased the amount of friction. B The wand was used to move air molecules around the car. C The gravitational force was decreased by bringing the paper closer to the car. D The paper wand had a magnet inside that attracted the metal car.

D. The property of magnetism is a physical property of metal. The magnet in the wand would attract the metal of the car.

Solutions are composed of two parts: the solute, and the solvent. What is the solute? A The substance with the greatest density. B The size of the particles that are dissolved. C The water that is used to dissolve a material. D The substance that is dissolved in the solvent.

D. The solute is the substance that is dissolved in the solvent. For example, if you dissolve sugar in water, the solute is the sugar and the solvent is the water.

Which of the following is an example of a heterogeneous mixture? A coffee B vinegar C salt dissolved in water D vegetable soup

D. Vegetable soup is a heterogeneous mixture. Heterogeneous mixtures do not have uniform composition throughout. Each spoonful of soup will have a different composition; some will have only broth, some vegetables, some broth and vegetables, etc.

....... are negative and in the cloud

Electrons

....... have a definite volume, but no fixed shape, so they take on the shape of their container. The particles of a liquid are close together, but not packed, and move around more freely than those of a solid.

Liquids

.......Matter is anything that has mass and takes up space.

Matter

...... are semiconductors, with properties in between metals and nonmetals.

Metalloids

............. are electrically neutral particles made of two or more atoms joined together by a molecular bond. Water (H2O) is a molecule. In water, two hydrogen atoms form a molecular bond with one oxygen atom. Oxygen (O2) and nitrogen (N2) in the atmosphere are also molecules because they are made of two atoms.

Molecules

........ are neutral and in the nucleus

Neutrons

....... do not conduct electricity.

Nonmetals

...... are positive and in the nucleus

Protons

......., mixtures in which one substance dissolves in another, are found all throughout nature. Air, lemonade, blood, and bronze are all examples of solutions. Solutions have two parts:. The ...... is the material that is dissolved in the ....... Solutions are always homogeneous mixtures, but homogeneous mixtures are not always solutions.

Solutions solute solvent

...... are found in the middle of the table (gray section below). They tend to be solid at room temperature, electrically conductive, shiny, and malleable.

Transition metals

Valence electrons are the electrons in the outermost orbit of an atom in its lowest energy state, or ground state. For example, potassium has a single valence electron. Elements tend to gain, lose, or share electrons until they have 8 valence electrons (known as a complete octet). Elements without a complete octet have high reactivity and low stability.

Valence electrons

If we add a substance to water that makes more H's than OH's, it becomes an ....., or if we add a substance to the water that makes more OH's than H's, it becomes a .......

acid base

Each kind of element has a unique number of protons, identified as its ..........

atomic number

However, specific signs help identify a change as .......: gas production (bubbles), light production (fire), a change in temperature (release or absorption of energy), unexpected color change, the production of a precipitate (formation of a solid from two solutions), and/or rust indicate a chemical change.

chemical

A ........ alters the chemical composition of a material. Chemical changes rearrange atoms to form products with new chemical and physical properties. Many chemical changes take place in daily life. Photosynthesis, the digestion of food, frying an egg, and baking bread are a few examples of chemical change.

chemical change

A ......... rearranges the atomic bonds between atoms, to form a new substance. There are two types of atomic bonds: ionic bonds and molecular bonds.

chemical reaction

The ..... of the periodic table are arranged according to the number of valence electrons in the atom.

columns

During ......., as a substance is cooled, it gives off heat, changing phase from a gas to a liquid.

condensation

Electrical ........ is how well a material allows electricity to flow through it, and is a physical property of matter. T

conduction

The electrons in electrical ........ move freely through the material. Most metals are good conductors. The wires in an electric circuit are usually metal, so they do not resist the flow of electrons. When a voltage is established across a conductor, a current can flow.

conductors

Matter and energy are ....... in physical and chemical changes. They might "hide" as another form of matter or energy, or move to another place, but the total amount of matter and energy in a closed system does not change.

conserved

For example, the melting point of ice is 32 degrees fahrenheit (0°C). Imagine a block of ice at 20 degrees fahrenheit. If you heat the ice, its temperature rises. Once the temperature reaches 32 degrees, adding more heat ........ raise the temperature of the ice. Instead, it produces a phase change from ice to water. The ice continues to absorb heat, but stays at 32 degrees fahrenheit until it is melted. Once melted, continued heating will again raise the temperature of the water.

does not

Each type of atom is known as an .......

element

Each type of atom is known as an .......... For example, hydrogen (H) is an element and helium (He) is a different element.

element

During ....... a substance absorbs heat and changes phase from a liquid to a gas.

evaporation

The particles of a ..... are farther apart and move so quickly that they fill all available space. Gases do not have a fixed shape or volume; they take the shape of their container.

gas

In the ......, the electrons in the atom are arranged so the atom has its lowest possible energy.

ground state

The substances in a ........ are not uniformly mixed. A box of granola with raisins and chunks is a heterogeneous mixture. Some scoops will have more raisins than others.

heterogeneous mixture

A ........ is uniform throughout the mixture. This means any sample of the mixture will have the same ratio of parts. A well-dissolved beaker of saltwater is a homogeneous mixture, as are laundry detergent and soapy water.

homogeneous mixture

Elements in the far right column of the periodic table, such as helium (He), neon (Ne), and argon (Ar), have full valence shells (helium has 2 valence electrons and the others each have 8). Such elements are chemically ......, meaning they rarely react with other elements.

inert

The electrons in electrical ........, such as materials like wood, glass, plastic, and air, stay close to their respective nuclei, making them poor conductors of electricity.

insulators

In an ........., electrons are removed from one atom and given to an atom of another element. The two particles have opposite charges and attract each other by the electromagnetic force, which bonds the two particles together.

ionic bond

The ........ also appears in each cell of the periodic table. It represents the average mass (in Atomic Mass Units, AMU) of one atom of the element. The mass number is usually a decimal number because it is an average; the number of neutrons in an element's nucleus can vary.

mass number

All ...... is made of particles called atoms, the smallest division of any element.

matter

When a solid is heated, the temperature of the solid rises until it reaches its .............. When the temperature reaches its melting point, adding heat does not raise the temperature any further until after a phase change is complete.

melting point

The valence electrons in ...... are loosely bound to each atom, so metals are shiny and good electrical conductors.

metals

A .... is produced by a physical change. Mixing changes the arrangement of particles, but does not produce materials with new chemical and physical properties. Other examples of physical changes are breaking, grinding, or cutting a material. For example, wind, water, and sand produce physical changes as they erode rocks. Humans make physical changes to forests during logging operations.

mixture

In a ......, the atoms, molecules, or particles of two or more different materials are mixed together but are not chemically combined.

mixture

In a............, electrons are shared between atoms. Molecular bonds are sometimes called ...........

molecular bond covalent bonds

A water molecule, H2O, breaks into an H and an OH ion. The H part is makes the solution an acid and the OH part makes the solution a base. When the number of H's in a solution equals the number of OH's, the substance is said to be ...... or pH balanced.

neutral

Pure water is ...... because for each water molecule that breaks apart, 1 H and 1 OH are left.

neutral

The ...... indicates how acidic or basic a substance is. 0 is very acidic, 7 is neutral, and 14 is very basic. The inside of batteries, orange juice, vinegar, and tomatoes are acids. Soap, bleach, baking soda solution, and drain cleaner are bases.

pH scale

The ......... of elements groups elements according to common physical and chemical properties. Elements in a column are similar to each other.

periodic table

The .........is a chart of the elements, organized by their atomic number and the physical and chemical properties.

periodic table

Materials can change state, for example from a solid to a liquid, when heat energy is added or removed. A change of state is called a phase change.

phase change

A ........ may change the appearance of a material but does not change its chemical composition. For example, a phase change, or changing the state of water (solid, liquid, gas), is a physical change.

physical change

A ......... consists of only one type of atom or molecule.

pure substance

A ..... has particles packed together in relatively fixed positions and has a definite shape and volume.

solid

In ,,......., a pure solid changes directly into a gas.

sublimation