Unit #1: INTRODUCTION

1. Unit #1: INTRODUCTION INTERNET REVIEW GAME Chapter 1: Matter and Energy Chemistry Is a Physical Science Matter and Its Properties Elements

2. Q1: Define a physical property. List two examples of physical properties. Answer: A property that can be observed or measured without changing the identity of the substance. Examples include color, odor, length, size and melting point.

3. Q2: How can you tell the difference between an element and a compound? Answer: Compounds can be separated into elements by chemical means. Elements cannot be separated into simpler substances by chemical means.

4. Q3: Identify each of the following as either a physical change or a chemical change. Explain your answers. a. A piece of wood sawed in half b. Milk turns sour c. Melted butter solidifies in the refrigerator Answer: a. physical, because the wood remains wood b. chemical, because the milk changes composition, as signified by the change in flavor c. physical, because the butter remains butter

5. Q4: Write a brief paragraph that shows that you understand the following terms and relationships between them: atom, molecule, compound and element Answer: A molecule is the smallest unit of a substance that keeps all of the physical and chemical properties of that substance. An element is composed of molecules that can be single atoms or more than one kind of the same atom. A compound is composed of two or more elements, so a molecule of a compound is made up of two or more different kinds of atoms.

6. Q5: Pick an object that you can see right now. List three of the object’s physical properties that you can observe. Can you also observe a chemical property of the object? Explain you answer. Answer: Obviously your answers will vary. Physical properties include shape, texture, state of matter, and taste. Chemical properties could not be observed unless a chemical change was attempted.

7. Q6: Magnesium reacts with hydrochloric acid to produce magnesium chloride and hydrogen gas. The reactants in this reaction are a. magnesium and magnesium chloride b. hydrochloric acid and hydrogen gas c. magnesium and hydrochloric acid d. magnesium chloride and hydrogen gas Answer: c. magnesium and hydrochloric acid

8. Q7: Matter that has a definite shape and a definite volume is a. a liquid b. an element c. a solid d. a gas Answer: c. a solid

9. Q8: We know that air is a mixture and not a compound because a. it can be heated to a higher temperature b. it can be compressed to a smaller volume c. it is colorless d. its composition can vary Answer: d. its composition can vary

10. Q9: Matter can be defined as anything that a. has weight b. has mass and volume c. is uniform throughout d. exhibits both chemical and physical properties Answer: b. has mass and volume

11. Q10: Which of the following is best classified as a homogenous mixture? a. pizza b. blood c. hot tea d. copper wire Answer: c. hot tea

12. Q11: A compound differs from a mixture in that a compound a. contains only one element b. varies in chemical compositiondepending on the sample size c. has a definite composition by mass of elements that the compound contains d. can be classified as either heterogeneous or homogeneous Answer: c. has a definite composition by mass of elements that the compound contains

13. Q12: Which of the following is not a physical state of matter? a. solid b. gas c. element d. liquid Answer: c. element

14. Q13: Three of the following must contain two or more kinds of atoms. Which one does not contain two or more kinds of atoms? a. element b. compound c. homogeneous mixture d. heterogeneous mixture Answer: a. element

15. Q14: Which of the following symbols does not match the element given? a. Al, Aluminum b. Co, copper c. K, potassium d. P, phosphorus Answer: b. copper is actually Cu

16. Q15: In trying to identify a sample of a pure substance, we observe the following properties. Tel whether each one is a chemical property or a physical property. a. Its mass is 124.3 g b. It is a shiny solid at room temperature c. It is easily etched by nitric acid d. It melts when heated to 670oC e. It is 31.7 centimeters long f. It is a good heat conductor g. It burns in air h. It is a good conductor of electrical energy Answer: Observations c and g are chemical properties; the others are physical properties

17. Q16: Describe the difference between a chemical change and a physical change. Give one example of each kind of change. Answer: In a chemical change, one or more of substances are converted into different substances. A physical change does not involve a change in the identity of the substances present. Examples will vary.

18. Q17: Describe general properties of metals, nonmetals and metalloids. Answer: • Metals: shiny, good conductors of heat; good conductors of electricity; malleable or ductile; most are solids at room temperature. • Nonmetals: poor conductors of heat and electricity; many are gases at room temperature; those that are solids are brittle rather than malleable or ductile. • Metalloids: properties are between those of metals and nonmetals.; less malleable than metals but not as brittle as solid nonmetals; most are semiconductors of electricity.