Chemistry Notes Chapter 2

1. Chemistry Notes Chapter 2

2. Describing Matter • Properties used to describe matter can be classified as extensive or intensive.

3. mass • a measure of the amount of matter that an object contains; the SI base unit of mass is the kilogram • volume • a measure of the space occupied by a sample of matter (2.1)

4. extensive property • a property that depends on the amount of matter in a sample • intensive property • a property that depends on the type of matter in a sample, not the amount of matter

5. Identifying Substances • substance • matter that has a uniform and definite composition; either an element or a compound; also called pure substance

6. Every sample of a given substance has identical intensive properties because very sample has the same composition. • Gold and copper are examples of substances, which are also referred to as pure substances.

7. physical property • a quality or condition of a substance that can be observed or measured without changing the substance's composition

8. malleable which means can be hammered into sheets without breaking

10. States of Matter • Three states of matter are solid, liquid, and gas.

15. solid • a form of matter that has a definite shape and volume

16. liquid • a form of matter that flows, has a fixed volume, and an indefinite shape

17. gas • a form of matter that takes the shape and volume of its container; a gas has no definite shape or volume

18. The words vapor and gas are sometimes used interchangeably. But there is a difference • The term gas is used for substances, like oxygen, that exist in the gaseous state at room temperature. (Gaseous is the adjective form of gas.)

19. Vapor • describes the gaseous state of a substance that is generally a liquid or solid at room temperature

20. Physical Changes • physical change • a change during which some properties of a material change, but the composition of the material does not change

21. Words such as boil, freeze, melt, and condense are used to describe physical changes. So are words such as break, split, grind, cut, and crush.

22. Physical changes can be classified as reversible or irreversible.

23. 1) Key Concept Name two categories used to classify properties of matter.Hint • (2) Key Concept Explain why all samples of a given substance have the same intensive properties.Hint • (3) Key Concept Name three states of matter.Hint

24. 4) Key Concept Describe the two categories used to classify physical changes.Hint • (5)Which property in Table 2.1 can most easily distinguish sodium chloride from the other solids? • (6)In what way are liquids and gases alike? In what way are liquids and solids different?

25. 7)Is the freezing of mercury a reversible or irreversible physical change? Explain your answer. • (8)Explain why samples of gold and copper can have the same extensive properties, but not the same intensive properties

26. Chapter 2, Section 2 • Classifying Mixtures

27. mixture • a physical blend of two or more substances that are not chemically combined

28. Based on the distribution of their components, mixtures can be classified as heterogeneous mixtures or as homogeneous mixtures.

29. heterogeneous mixture • a mixture that is not uniform in composition; components are not evenly distributed throughout the mixture

30. homogeneous mixture • a mixture that is uniform in composition; components are evenly distributed and not easily distinguished

31. solution • a homogeneous mixture; consists of solutes dissolved in a solvent

32. phase • any part of a sample with uniform composition and properties

37. Separating Mixtures • Differences in physical properties can be used to separate mixtures.

38. filtration • a process that separates a solid from the liquid in a heterogeneous mixture

39. distillation • a process used to separate dissolved solids from a liquid, which is boiled to produce a vapor that is then condensed into a liquid

41. 11) Key Concept How are mixtures classified?Hint • (12) Key Concept What type of properties can be used to separate mixtures?Hint • (13)Explain the term phase as it relates to homogeneous and heterogeneous mixtures?

42. 14)Classify each of the following as a homogeneous or heterogeneous mixture. • food coloring • ice cubes in liquid water • mouthwash • mashed, unpeeled potatoes

43. 15)How are a substance and a solution similar? How are they different? • (16)In general, when would you use filtration to separate a mixture? When would you use distillation to separate a mixture? • (17)Describe a procedure that could be used to separate a mixture of sand and table salt

44. Elements and Compounds

45. element • the simplest form of matter that has a unique set of properties; an element cannot be broken down into simpler substances by chemical means (2.3)

46. compound • a substance that contains two or more elements chemically combined in a fixed proportion (2.3)

47. Compounds can be broken down into simpler substances by chemical means, but elements cannot.

48. Breaking Down Compounds • Physical methods that are used to separate mixtures cannot be used to break a compound into simpler substances

49. chemical change • a change that produces matter with a different composition than the original matter (2.3)