Chapter 2 Review
Section 2-1
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SUMMARY
Compostition of Matter
Be able to define matter; atoms, elements, compounds
Classification of matter
Classify matter into pure substance (E or C), or Mixture (Soln, Sol. M, Susp, or Col.)
Classify as Heterog or Homog. Material
> Matter has mass and occupies space.
> An element is a substance that cannot be broken down into simpler substances.
> An atom is the smallest unit of an element that has the properties of the element.
> Atoms can combine to form molecules or compounds.
> Chemical formulas represent the atoms in compounds and molecules.
> A mixture is a combination of two or more pure substances. Mixtures can be categorized as heterogeneous or
homogeneous.
Section 2-2 Properties of Matter
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SUMMARY
Define and identify Physical Properties
Define and identify Chemical Properties
Density problems: Density is a physical property
Characteristic properties help to identify and classify matter.
> Physical properties can be observed or measured without changing the composition of matter.
> Physical properties help determine how substances are used.
> The density of a substance is equal to its mass divided by its volume.
> Chemical properties describe how a substance reacts; they can be observed when one substance reacts with
another.
> Scientists use characteristic properties to identify and classify substances.
Section 2-3 Changes in Matter
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Define and identify Physical Changes
Mixtures are easily separated by physical changes. (LAB)
Define and identify Chemical Changes
Describe and apply the Law of Conservation of Mass
Know the 5 indicators of Chemical reactions. (LAB)
SUMMARY
> Physical changes are changes in the physical properties of a substance that do not change the identity of the
substance.
> Changes of state are physical changes.
> Dissolving is a physical change.
> Physical changes are often easily reversed.
> Chemical changes form new substances that have new properties. Chemical changes can be reversed only through
chemical reactions.
> Chemical changes often cause changes in color or produce sound, light, odor, or heat.
Complete practice review pg 60- 61
problems (1-14, 16, 18, & (20-23)
Understanding Concepts
1. C
2. D
3. A
4. C
5. A
6. C
7. C
Using Vocabulary
8. Answers will vary. Student answers may include: melting point, boiling point, density, reactivity with acid,
color, hardness, texture, flammability, malleability, thermal conductivity, and solubility.
9. a. An atom is the smallest unit of an element that has the properties of the element; a molecule is the smallest
unit of a substance that exhibits all of the properties characteristic of that substance.
b. A molecule is an individual particle that is composed of 2 or more atoms of either the same or different
elements; a compound is a substance that is composed of atoms of two or more elements.
c. A compound is made of 2 or more different elements that are chemically combined; a mixture is a combination
of 2 or more pure substances physically mixed together.
10. Wood has the chemical property of flammability, meaning it burns in the presence of oxygen. This is a
chemical change, not a physical change, because new substances with properties that are different from wood
are created; also heat (a sign of a chemical change) is present.
11. a mixture, because dissolving (a physical change) has occurred; It can be separated into its components, the
sugar and water are mixed physically, it does not have a fixed composition or definite properties, it is formed
from two pure substances (sugar and water).
12. miscible; miscible (two or more liquids that are able to dissolve), vs. immiscible (two or more liquids that do
not dissolve)
13. Energy (as heat and light) is released; the properties of the magnesium change.
14. physical properties: color, density, magnetism, melting point, boiling point, dissolving, conducting electricity;
chemical properties: reactivity, corrosion, flammability
Building Math Skills
16. D = 67.5 g/15 cm3 = 4.5 g/cm
3
18. V = 510 g/(8.4 g/cm ) = 61 cm
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3
20. V = 63.4 mL = 40.0 mL
V = 23.4 mL = 23.4 cm3
M = 8.9 g/cm3 =23.4 cm3
m = 210 g
Thinking Critically
21. glycerin (because it is less dense); density of glycerin =37.8 g/30.0 mL = 1.26 g/mL; density of corn syrup =
82.8 g/60.0 mL = 1.38 g/mL
22. Sample answer: Pass the mixture through a filter that allows the salt and pepper to pass through but traps the
pebbles. Mix the salt and pepper with water to dissolve the salt. Filter the mixture to trap the pepper. Evaporate
the water to recover the salt.
23. The powder is a compound. The change in color and the formation of a gas imply that a chemical change took
place. Compounds can be broken down by chemical changes.