Chapter 1

1. What is Chemistry? Chapter 1

4. 1.1 Science and Technology (Continued) • Chemistry • Referred to as the “central science” • Bridges between physics and biology • Biochemistry • Material science

5. 1.1 Science and Technology (Continued) • Chemistry • The study of matter and the transformations it undergoes • Matter—“stuff” • Anything that has mass and occupies space • Transformation—“change” • Changes inmatter

6. Classifying Matter: States of Matter

7. Molecules in a Solid, Liquid, & Gas

8. 1.2 Matter (Continued)

9. Classifying Matter

10. Matter and its Representation What we observe… To what we can’t see! Chemical symbols allow us to connect…

11. Elements • The elements are recorded on thePERIODIC TABLE • There are 117 recorded elements at this time.

12. 1.2 Matter (Continued) • Elements • Basic building block of all matter • Organized in the periodic table • Roughly 113 known (90 natural, 23 synthetic)

13. The Nature of Matter Chemists are interested in the nature of matter and how this is related to its atoms and molecules. Gold Mercury

14. Crystal Structures: Ag & Au

15. Chemical compounds are composed of two or more atoms. Chemical Compounds

16. Chemical Compounds Ionic Compound Iron pyrite (FeS2) Molecule: Ammonia (NH3)

17. Chemical Compounds • All Compounds are made up of molecules or ions. • A molecule is the is the smallest unit of a compound that retains its chemical characteristics. • Ionic compounds are described by a “formula unit”. • Molecules are described by a “molecular formula”.

18. Molecular Formula • A molecule is the smallest unit of a compound that retains the chemical characteristics of the compound. • Composition of molecules is given by a molecular formula. C8H10N4O2 - caffeine H2O

19. Physical Properties • Some physical properties: • Color • State (s, g or liq) • Melting and Boiling point • Density (mass/unit volume) • Extensive properties(mass) depend upon the amount of substance. • Intensive properties(density) do not.

20. 1.2 Matter • Matter • Anything that has mass and occupies space • Your textbook • Has a mass and has a volume associated with it • Air • Has a mass and has a volume associated with it • A filled tank of air has more mass than an empty tank. • Fills a space such as the volume of the tank

21. 1.2 Matter (Continued) • Chemistry begins to define matter by two broad types: • Pure substance • Only a single type of matter • Table salt (sodium chloride) • Table sugar (sucrose) • Mixture • Two or more substances intermixed • Mixture of salt and sugar • Rocks (many different minerals present)

22. 1.2 Matter (Continued) • Mixtures are further divided as follows: • –Homogenous mixture • Homo- means “the same.” • Composition of mixture is uniform. • A cup of tea with sugar dissolved throughout. • – Heterogeneous mixture • Hetero- means “different.” • Composition is not the same throughout. • Different samples will have different ratios of components. • Different areas of rocks would have different mineral ratios.

23. 1.2 Matter (Continued) • Classify the following examples of matter as pure substances, heterogeneous mixtures, or homogeneous mixtures(solutions): (a) Piece of wood • Iron nail • Rusty iron nail (d) Well-stirred mixture of food dye and water (e) Bees wax and candle wax mixed together by hand (f) Bees wax and candle wax melted together, stirred well, then allowed to solidify

24. Classifying Matter

25. Physical Properties O H H Physical properties are a function of intermolecular forces. Water (18 g/mol) liquid at 25oC Methane (16 g/mol) gas at 25oC H • Water molecules are attracted to one another by • “hydrogen bonds”. • Methane molecules only exhibit week “London • Forces”. C H H H

26. Physical Properties Physical properties are affected by temperature (molecular motion). The density of water is seen to change with temperature.

27. Physical Properties Mixtures may be separated by physical properties:

28. 1.2 Matter (Continued) • Types of substances • Elemental substance • Pure substance made of only one type of atom • Pure Gold is Au. • Oxygen in the air is O2. • Compound • Pure substance made of two or more different elements • Water (H2O) is made of hydrogen and oxygen.

29. 1.2 Matter (Continued) • Chemical formula • The number of each type of atom that makes up the smallest unit of the compound • Examples: • Water (H2O) is 2 H atoms and one O atom. • Table sugar (C12H22O11) is 12 C atoms, 22 H atoms, and 11 O atoms.

30. Chemical Properties • Chemical properties are really chemical changes. • The chemical properties of elements and compounds are related to periodic trends and molecular structure.

31. Hyrdogen Balloon Ignited

32. Chemical Properties A chemical property indicates whether and sometimes how readily a material undergoes a chemical change with another material. For example, a chemical property of hydrogen gas is that it reacts vigorously with oxygen gas.

33. Reaction of Al + Br2

34. A Chemist’s View of Water Macroscopic H2O (gas, liquid, solid) Symbolic Particulate 2 H2(g) + O2 (g)  2 H2O(g)

35. Water Droplet/Molecules

36. 1.2 Matter (Continued) • Elements • Many names are familiar. • Carbon, silver, gold, iron, and aluminum • Represented by 1-, 2-, or 3-letter symbols: • Taken from English (C = carbon, Al = aluminum) • Taken from Latin (Fe = ferrum, Au = aurum) • Taken from another language (W = wolfram)

37. 1.2 Matter (Continued) • Atoms • Smallest unit of an element • Cannot be seen through normal microscopes • First images were received in the early 1980s by a scanning tunneling microscope.

38. 1.2 Matter (Continued) Which of the following is a pure substance, a homogenous mixture, and a heterogeneous mixture? Pure water Powdered lemonade Fresh-squeezed lemonade pure substance homogenous mixture heterogeneous mixture

39. 1.2 Matter (Continued) Which of the following are compounds? (a) iron oxide (Fe2O3) • ozone (O3) • iron (Fe) (d) carbon monoxide (CO) (e) propane (C3H8)

40. 1.2 Matter (Continued) Which of the following are compounds? (a) iron oxide (Fe2O3)—compound • ozone (O3) • iron (Fe) (d) carbon monoxide (CO)—compound (e) propane (C3H8)—compound

41. 1.3 Matter and Its Physical Transformations • Physical transformation • The same substance, but a different state of matter after transformation • States of matter • Solid • Liquid • Gas

42. 1.3 Matter and Its Physical Transformations (Continued) • Physical changes in water • Freezing is liquid changing to solid; melting is the reverse. • Vaporization is liquid changing to gas; condensation is the reverse. • Sublimation is a solid changing directly to a gas.

43. 1.3 Matter and Its Physical Transformations (Continued)

44. 1.3 Matter and Its Physical Transformations (Continued) Ice cubes slowly vanishing while stored in a freezer is an example of: • Vaporization • Condensation (c) Melting (d) Sublimation

45. 1.3 Matter and Its Physical Transformations (Continued) Ice cubes slowly vanishing while stored in a freezer is an example of: • Vaporization • Condensation (c) Melting (d) Sublimation

46. 1.4 Matter and Its Chemical Transformations • Chemical change (chemical transformation) • When a substance changes to a different substance or substances • Combining oxygen and hydrogen gas with a spark will create water (H2O). • Chemical properties are described when a substance undergoes chemical changes.

47. Rusting Iron

49. 1.4 Matter and Its Chemical Transformations (Continued)

50. 1.4 Matter and Its Chemical Transformations (Continued) • Chemical reaction—describes a chemical transformation Na(s) + Cl2(g)  2NaCl(s) • Reactants–the starting substances • Products–the newly formed substances • Sodium and chlorine react to give sodium chloride.