Science 391-Physical and Chemical Properties
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? the production of bubbles flames a change in color Any of the above could indicate a chemical reaction has taken place.
Any of the above could indicate a chemical reaction has taken place. All of these observations could indicate that a chemical reaction has taken place.
A teacher places the following items into a container: sand, a sponge, pebbles, rocks, coral, tree bark, and water. The teacher has students place their hands in the container, without looking at the items, to feel the items and guess what they are. How could she best use this activity to move into a lesson on physical properties? Ask the students how the items might have formed. Ask the students to match the picture of each item with its name. Ask the students which items were scary to touch. Ask the students how they would group the different items and why.
Ask the students how they would group the different items and why. A discussion on how to group the items could lead to a discussion about what physical properties are.
Which of the following represents an element? (choose all that apply) Select all answers that apply. NaCl (salt) H₂O (water) C (carbon) N₂ (nitrogen gas)
C (carbon) N₂ (nitrogen gas) Carbon is a single type of atom and is therefore an element. Nitrogen gas, N₂ is an element because it consists of a single type of atom. It is also a molecule because it consists of 2 atoms held together by a molecular bond.
When oxygen and hydrogen combine to form water, what type of change has occurred? Nuclear Electrical Physical Chemical
Chemical When oxygen and hydrogen combine to form water, a chemical change has occurred. The oxygen and hydrogen have formed a new substance.
Which of the following describes a molecule? Atoms of a single element joined together by ionic bonds. Electrically neutral particles of two or more atoms joined by molecular bonds. A mixture of two or more atoms, with no chemical bond between them. Groups of two or more different elements joined by ionic or molecular bonds.
Electrically neutral particles of two or more atoms joined by molecular bonds. 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 statements is true regarding electrons? Electrons are negatively charged particles located inside and outside of the nucleus of the atom. Electrons are positively charged particles that orbit around the outside of the nucleus of the atom. Electrons are negatively charged particles located inside the nucleus of the atom. Electrons are negatively charged particles that orbit around the outside of the nucleus of the atom.
Electrons are negatively charged particles that orbit around the outside of the nucleus of the atom. Electrons are negatively charged particles that orbit around the outside of the nucleus of the atom.
Which of the following describes a compound? Groups of two or more different elements held together by ionic or molecular bonds. Electrically neutral particles made of two or more atoms joined together by molecular bonds. Atoms of a single element joined together by ionic or molecular bonds. Atoms that are mixed together without a chemical bond.
Groups of two or more different elements held together by ionic or molecular bonds. Compounds form from two or more different elements, and can have either ionic or molecular bonds.
Which of the following is an example of a molecule? H₂O (water) NaCl (salt) Ne (neon) None of the above are molecules.
H₂O (water) Water, H₂O is a molecule. It is formed from 3 atoms held together by molecular bonds.
Which of the following is an example of a compound? N₂ (nitrogen gas) Fe (iron) O₂ (oxygen gas) H₂O (water)
H₂O (water) 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.
Gases are often difficult to see so students might interpret a phase change from a liquid to a gas as if the liquid had disappeared. What is the best way for an elementary school teacher to use an interactive simulation showing drawn molecules in a phase change from a liquid to a gas? Sign up for a computer lab so students can watch the simulation in pairs. Ask students to play w/ the simulation & make observations. When students are finished, have them answer questions about what they saw. Save the simulation for a time when a substitute teacher is present so the substitute has something to do w/ the students. Project the simulation for the class. Run the simulation & explain what is happening as the students watch. After the simulation, check for understanding by asking questions about what the students saw. Project the simulation for the class while performing the same experiment for the class using water, hea
Project the simulation for the class while performing the same experiment for the class using water, heat, and ice. Ask students what to do (turn on the heat, bring in the ice). While repeating each action, ask for students' observations and explanations of what they see and what the molecular behavior means. By watching the simulation and the actual experiment together as a class, and having students concurrently describe what they see and what they think is happening, the teacher can hear student interpretations of what they see and correct any misconceptions by asking probing questions. Discussions among students with differing opinions can lead to deeper understanding.
Solutions are composed of two parts: the solute, and the solvent. What is the solute? The size of the particles that are dissolved. The substance that is dissolved in the solvent. The substance with the greatest density. The water that is used to dissolve a material.
The substance that is dissolved in the solvent. 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.
2nd grade teacher wants to check for understanding of the difference between an element & a compound before she goes on with the rest of the lesson. Which activity will best help her check the understanding of each student? -Teacher hands out a sheet w/ pictures of elements & compounds, asks students to put a box around all of the elements & underline all of the compounds. She collects the sheets, grades them at night, & returns them the next day. -Teacher randomly calls on students to describe the difference between elements & compounds. -Teacher asks students to stand in an empty area in the classroom. One at a time, she asks students to move around & make themselves into an element, then into a compound. She observes the class. -Teacher gives each student 3 small piles of differently colored beads. One at a time, she asks students to make an element, then a compound. After each instruction she walks the class to
The teacher gives each student 3 small piles of differently colored beads. One at a time, she asks students to make an element, and then a compound. After each instruction she walks the class to observe. With this activity the teacher can immediately check the understanding of each individual student and remediate as she walks around.
2nd grade teacher wants to check for understanding of the difference between a heterogeneous & a homogeneous mixture before she goes on w/ the lesson. Which activity will best help her check the understanding of each student? -Teacher randomly calls on students to describe the difference between the 2 mixtures. -Teacher hands out a sheet w/ pictures of heterogeneous & homogeneous mixtures, asks students to circle all the heterogeneous mixtures & underline all the homogeneous mixtures. She collects the sheets, grades them at night, & returns them the next day. -Teacher asks students to stand in an empty area in the room. One mixture at a time, she asks students to move around, make themselves into a heterogeneous, & then a homogeneous mixture. She observes the class. -Teacher gives each student 3 small piles of differently colored beads. One mixture at a time, she asks students to make a heterogeneous, then a homogen
The teacher gives each student 3 small piles of differently colored beads. One mixture at a time, she asks students to make a heterogeneous, and then a homogeneous mixture. After each instruction she walks the class to observe. With this activity the teacher can immediately check the understanding of each individual student and remediate as she walks around.
Is matter conserved during a chemical change? No, because less matter is present after atoms combine by forming chemical bonds. Yes, because the same total number of atoms exist before and after the reaction, only the types of atoms have changed. No, since atoms are rearranged during a chemical change, the number and types of atoms also change. Yes, the atoms are rearranged during a chemical change, but the same number and types of atoms are still present.
Yes, the atoms are rearranged during a chemical change, but the same number and types of atoms are still present. 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.
Which of the following is the best example of a homogeneous mixture? trash in a kitchen wastebasket a bag of rice a bowl of Raisin Bran cereal and milk Caesar salad
a bag of rice Rice in the bag is uniformly mixed; therefore, it is a homogeneous mixture.
Condensation occurs when: a gas cools to its boiling point temperature. a liquid is cooled to its melting point temperature. a liquid is heated to its boiling point temperature. a solid is heated to its melting point temperature.
a gas cools to its boiling point temperature. 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.
Mr. Popov's students are building circuits. The ends of the conducting wires have alligator clips that students use when making connections. Mr. Popov notices that several students are connecting the alligator clips to the plastic that coats each of the conducting wires instead of connecting the metal clips to metal. What did Mr. Popov specifically forget to include in his lesson plans? ability grouping cautioning students about safety rules when working with electricity activating students' prior knowledge about conductors and insulators demonstrating exactly how to set up the circuits
activating students' prior knowledge about conductors and insulators Mr. Popov would have been wise to activate students' prior understanding about insulators and conductors, including that metals are conductors and insulators are not. Then, when a circuit does not work, students might recall that they must connect metal to metal when making a complete circuit.
Nitrogen gas, N2, is classified as which of the following? an element a compound a solvent a salt
an element A molecule is an element if it consists only of elements with the same number of protons.
Which are the smallest particles of an element? atoms protons molecules compounds
atoms Atoms are the smallest particles of an element. If broken into protons, neutrons, and electrons, the element no longer exists.
Which of the following is an example of a chemical change? melting ice cream boiling water chopping wood baking a cake
baking a cake 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.
Which of the following is an example of a physical change? boiling water to make pasta toasting bread browning ground beef roasting garlic
boiling water to make pasta Boiling water is a physical change. It is only a change in the state of matter (water to gas), not in the composition.
Which of the following best describes an ionic bond? bonds that form when iron atoms combine with arsenic bonds that form by physical means in a mixture bonds that form when electrons are removed from one atom and given to an atom of another element bonds that form when electrons are shared between atoms
bonds that form when electrons are removed from one atom and given to an atom of another element Ionic bonds are bonds that form between two oppositely charged atoms after one of the atoms has donated electrons to the other.
Examples of Changes in Matter "X" Changes Chemical Changes Melting an ice cube Burning a piece of wood Tearing a piece of paper "Z" "Y" Lighting a match Use the table to answer this question. Matter can undergo two types of changes. The table lists those two changes and some examples of each. Which term would best replace the letter "Y" in the table? frying an egg baking a cake breaking a mirror rotting a peach
breaking a mirror Breaking a mirror is an example of a physical change. Once you break the mirror you have pieces of the mirror, but you still have the same substance you had when you started. The mirror is still chemically a mirror; it just changed physically.
Which of the following characteristics always describes a gas? Select all answers that apply. rigid changing volume can be compressed (squashed) definite shape
changing volume can be compressed (squashed) A gas can change volume depending on pressure and temperature. A gas can be compressed.
When a substance undergoes a _____ change, one or more new substances are formed. chemical ecological natural physical
chemical 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.)
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? toxicity radioactivity chemical stability flammability
chemical stability A chemically unreactive element is chemically stable. It is unlikely to undergo a chemical reaction.
Methane (CH4) is classified as which of the following? compound element mixture solution
compound Methane is a compound because it is composed of two different elements held together by chemical bonds.
A material in which electrons move freely is called a: semiconductor. resistor. insulator. conductor.
conductor. 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.
A material in which heat moves freely is called a: insulator. conductor. resistor. semiconductor.
conductor. A material in which heat is free to flow is a conductor. Metals are often good conductors. An insulator prevents the flow of heat. For example, styrofoam is a good thermal insulator.
The water cycle is an example of which of the following? conservation of energy conservation of momentum conservation of matter conservation of charge
conservation of matter The amount of water does not change as it moves through the water cycle.
Which of the following object best conducts electricity? oxygen gas copper pure water wood
copper 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.
Which of the following is a chemical reaction? smashing a rock into pieces digesting food water boiling mixing oil and vinegar in a table dressing
digesting food Digestion changes the chemical compound of the food and is, therefore, a chemical reaction.
Which of the following particles can be found orbiting outside the nucleus of an atom? electrons photons protons neutrons
electrons Electrons have a negative charge and orbit outside the nucleus of an atom.
Which subatomic particles orbit around the nucleus of the atom? neutrons protons subtrons electrons
electrons The electrons orbit around the nucleus of the atom.
Which of the following tools is the best choice for separating a mixture of sand and water? filter paper mesh screen separation funnel distillation
filter paper The pores of filter paper are small enough that sand will remain in the filter whereas water will pass through.
Kim bought some fireworks to shoot off on the 4th of July. She noticed several different powders mixed together in the tube. As the fireworks were ignited, what evidence best indicates a chemical reaction had occurred? a change in state from a liquid state to a solid fire and an explosion the rocket falling apart in the atmosphere the various colored embers falling down
fire and an explosion There are indicators that show a chemical reaction has occurred: gas production (bubbles), change in temperature (release or absorption of energy), burning, color change, and/or production of a precipitate (formation of a solid) The fire and explosion are results of a chemical change.
Which of the following characteristics always describes a solid? Select all answers that apply. fixed volume always clear definite shape rigid
fixed volume definite shape rigid A solid has a fixed volume. A solid has a definite shape. A solid is rigid.
Which of the following is a chemical property? density hardness freezing point flammability
flammability 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.
Examples of Changes in Matter "X" Changes Chemical Changes 1. Melting an ice cube 1. Burning a piece of wood 2. Tearing a piece of paper 2. "Z" 3. "Y" 3. Lighting a match Use the table to answer this question. Matter can undergo two types of changes. The table lists those two changes and some examples of each. Which term would best replace the letter "Z" in the table? A forming rust on a piece of iron B crumpling a piece of paper C melting butter on an ear of corn D freezing a juice box in the freezer
forming rust on a piece of iron Forming rust on a piece of iron is an example of a chemical change. The rust is not iron; it's a new and different substance from what you started with.
Which atomic particles are located inside the nucleus? protons subtrons magnetrons electrons
protons The protons are located inside the nucleus of an atom.
All atoms of a single element have the same number of: protons. electrons. neutrons. all of the above.
protons. 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.
Which of these is a good electrical insulator? steel wool rubber copper saltwater
rubber The electrons in rubber generally stay in their respective atoms and do not easily conduct an electrical current, making rubber a good electrical insulator.
Salt water can be classified as which TWO of the following? Select all answers that apply. solution compound element mixture
solution mixture Salt water is a solution because it is a homogeneous mixture with salt dissolved in water. Salt water is a mixture because it is composed of particles of two or more different materials that are not chemically combined.
A liquid is heated to its boiling point temperature. If further heat is added to the liquid it will: stay at its boiling point temperature until all of the liquid has evaporated. increase in temperature as the liquid evaporates. increase in temperature but remain a liquid. decrease in temperature until all of the liquid has evaporated.
stay at its boiling point temperature until all of the liquid has evaporated. 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.
One of the most commonly used examples of a solution is: the atmosphere. a bowl of cereal. a peanut butter and jelly sandwich. the rock layers comprising the fossil record.
the atmosphere. 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.
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? the liquid water the lemonade powder the spoon the frozen ice
the liquid water 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.
Which of the following is an example of a heterogeneous mixture? coffee vinegar vegetable soup salt dissolved in water
vegetable soup 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.
Which of the following is an example of a physical change? photosynthesis lighting a candle mixing vinegar and baking soda water boiling
water boiling A physical change takes place when water boils. The process does not form a new substance.
Which of the following would be considered a phase change? A change in color as a material is heated. A change in state from a solid to a liquid. A change in the chemical properties of a substance when heat is added. A change in temperature due to a chemical reaction between two substances.
A change in state from a solid to a liquid. 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 describes the process of sublimation? Pure water breaks into charged ions of hydrogen and hydroxide. A pure liquid changes directly into a gas. The atoms in a material combine with pure oxygen. A pure solid changes directly into a gas.
A pure solid changes directly into a gas. In sublimation a pure solid experiences a phase transition directly to a gas.
Which of the following steps in making coffee involves a chemical change? grinding the coffee beans heating the water with a hot plate the water boiling in the kettle None of these.
None of these. All of the choices provided are physical, not chemical, changes.
Which activity would best help a kinesthetic learner understand the model of an atom? In a large open space, have students hold signs with "+", "-", or "0" on them. Group students so all "+" and "0" signs are clustered together in one place. Have all students with "-" signs run randomly around the central group. Show a simulation of an atom to the class and point out the positions of the nucleus, protons, neutrons, and electrons. Play a CD for the class that describes the structure of the atom and the location of its parts. Tell the class about the structure of the atom, explaining that protons and neutrons are in the center, held tightly together in something called the nucleus, and that electrons orbit around the nucleus.
In a large open space, have students hold signs with "+", "-", or "0" on them. Group students so all "+" and "0" signs are clustered together in one place. Have all students with "-" signs run randomly around the central group. A kinesthetic learner learns best when they use their body or hands to form, move, or manipulate objects.
Which of the following statements is true regarding protons and atoms? In an atom, the protons can be inside or outside the nucleus. In an atom the protons are located inside the nucleus, but they leave the atom when they collide with electrons. In an atom, the protons are located inside the nucleus. In an atom, the protons orbit outside of the nucleus of the atom.
In an atom, the protons are located inside the nucleus. Protons in an atom are located inside the nucleus, as are the neutrons.
What happens to a liquid when its temperature cools to its melting point temperature? It begins to melt. It begins to evaporate. It begins to become a gas. It begins to solidify.
It begins to solidify. 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.
Which of the following is the best example of a heterogeneous mixture? Apple cider in a big, tall, glass. Table salt in the salt shaker. Layered gravel at the bottom of an aquarium. Fine potting soil around a potted plant.
Layered gravel at the bottom of an aquarium. The layered gravel is not uniformly mixed, therefore, it is a heterogeneous mixture.
A frozen ice cream bar was left in the sun and melted. Which statement is true regarding the physical properties of the ice cream bar after it melted? Its molecules were less energetic after it melted. The arrangement of molecules had changed. Its molecules were larger after it melted. Its chemical composition had changed.
The arrangement of molecules had changed. The ice cream bar changed state from a solid to a liquid phase. A phase is a physical property and describes the current arrangement of the molecules. The molecules themselves, however, do not change.
A frozen popsicle was left in the sun and melted. Which statement is true? The temperature of the popsicle decreased. The volume of the popsicle increased. Energy was removed from the popsicle. The molecules started to move more and became more loosely packed.
The molecules started to move more and became more loosely packed. When something melts from a solid to a liquid, its molecules move faster and spread further apart.
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? The gravitational force was decreased by bringing the paper closer to the car. The wand increased the amount of friction. The wand was used to move air molecules around the car. The paper wand had a magnet inside that attracted the metal car.
The paper wand had a magnet inside that attracted the metal car. The property of magnetism is a physical property of metal. The magnet in the wand would attract the metal of the car.
A solid gold bar is melted in a smelter. Which of the following statements correctly compares the volume of the solid bar to the volume of the liquid gold? The volumes will be different because the solid holds its shape. The volumes will be different because the solid takes up less space than the liquid. The volumes will be the same because they both have the same number of molecules. The volumes will be the same because the surrounding pressures are the same.
The volumes will be different because the solid takes up less space than the liquid. Volume is a measure of space occupied. Although both have the same number of molecules, the heat needed to melt the gold increases the spaces between molecules in the liquid. The liquid will have a greater volume.
Boiling point temperature is NOT considered a chemical property of a material. Why is the boiling point temperature NOT classified as a chemical property? The procedure of turning a liquid into a gas is reversible. A boiling point temperature does not indicate flammability. When a substance evaporates, it does not become a new substance. The molecules in a gas are generally farther apart than the molecules in a liquid.
When a substance evaporates, it does not become a new substance. Chemical properties only describes situations in which the atoms and molecules in a substances interact to form a new substance.
Which of the following is an example of a chemical change? mixing baking soda and vinegar ice cream melting shattering glass sanding wood
mixing baking soda and vinegar Mixing baking soda and vinegar is a chemical change. A new substance, carbon dioxide, forms in the reaction.
Which of the following particles resides in the nucleus of an atom? Select all answers that apply. neutron electron proton neutrino
neutron proton The neutron is found in the nucleus of the atom. The proton is found in the nucleus of the atom.
Which type of change has taken place if a substance's shape, appearance, color and/or volume has changed? electrical chemical physical negative
physical A physical change has occurred if a substance's shape, appearance, color and/or volume has changed. A chemical change results in the formation of a new substance with new properties.
When a substance changes state, it undergoes a ____ change. natural ecological chemical physical
physical 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.
Examples of Changes in Matter "X" Changes Chemical Changes 1. Melting an ice cube 1. Burning a piece of wood 2. Tearing a piece of paper 2. "Z" 3. "Y" 3. Lighting a match Use the table to answer this question. Matter can undergo two types of changes. The table lists those two changes and some examples of each. Which term would best replace the letter "X" in the table? chemical physical natural neutral
physical All the examples in the left column of the table are physical changes because after the change takes place, you have the same substance you started with, water and paper—the substance just changes form.
A teacher places the following items into a container: sand, a sponge, pebbles, rocks, coral, tree bark, and water. The teacher has students place their hands in the container, without looking at the items, to feel the items and guess what they are. This activity would best illustrate which of the following concepts? transfer of energy properties of matter physical changes of matter mixing and separating items
properties of matter Shape and size are physical properties of matter. By touching the items, the students are able to feel the texture, size, and consistency of the items which are all physical properties.
Students in Mr. Polanski's class are learning about elements & compounds. Mr. P. has given each student an "atomic building kit" consisting of different colored balls w/ holes drilled into them & sticks that fit into the holes. Mr. P. shows students samples of a material, for ex: a chunk of coal or a shaker of salt, & explains which atoms are in the material, whether the material is formed from one type of atom or multiple types, & describes how the atoms combine. The students build a model of each material. As they build, Mr. P. explains what makes one material an element & another a compound. Which best completes the follow-up question Mr. P. uses to check for student understanding of the difference between elements & compounds? "If you were a science supply company making kits to show the difference between compounds and elements -what variety must be included in the kits, why?" -what material would you use for
what variety must be included in the kits, and why?" Students will have to express that compounds form from two different kinds of atoms, whereas elements form from a single kind of atom.
