Matter and Change

1. Matter and Change Chapter 3

2. Diatomic • Two atoms of the same element bonded together

3. Phase • A sample of matter that looks the same

4. Substance • A form of matter that has a uniform and unchanging composition…aka a pure substance

5. The 3 Physical States of Matter • Solid • Liquid • Gas

6. Solid • Definite shape and volume • Atoms/molecules held rigidly in place • Non-compressible

7. Liquid • No definite shape; takes the shape of its container; Non-compressible • Definite volume • Molecules are farther apart than those of a solid, allowing molecules to flow past one another

8. Gas • No definite shape nor volume • Gases take the shape & volume of their container • Gases are mostly empty space • Compressible

9. What is the physical state of each of the following at room temperature? • gold • gasoline • helium • bromine • lithium • nitrogen

10. The 3 Chemical Classes of Matter • Element • Compound • Mixture

11. 1. Element • A substance that can not be reduced to a simpler form • The building blocks of all substances • Made up of only one type of atom

12. 3 Types of Elements • Metals: to the left of the “stair-step.” They compose the majority of the elements • Non-metals: are to the right of the “stair-step” • Metalloids: are non-metals having some metallic characteristics

13. 2. COMPOUNDS • formed when 2 or more different elements join together chemically • made of 2 or more different kinds of atoms joined in a definite pattern/arrangement • are separated by chemical reactions into simpler substances

14. 2 Types of Compounds • ionic compounds: made up of a metal and a non-metal portion • covalent compounds: composed of non-metals

15. Which of these are elements and which of these are compounds? • Hg • NaCl • O2 • H2O • S8

16. 3. Mixtures • 2 or more distinct substances mixed together with variable composition • may have distinct phases • can be separated by physical methods • Distillation • Filtration • chromotography

17. 2 Types of Mixtures • Homogeneous • Heterogeneous

18. Homogeneous Mixture: aka Solution (sol’n) • Has a constant composition throughout • always has a single phase • can be any state of matter

19. Give me some examples of solutions in each of the 3 states of matter. gas: Air nitrous oxide(dentist) liquid: salt water 7-up solid: gold ring, metal alloys

20. Heterogeneous Mixture • A mixture that does not blend smoothly throughout • 2 or more distinct phases are visible

21. What are some examples of a heterogeneous mixture?

22. Which of the 3 are substances? • Elements • Compounds • Mixtures

23. Classify each of the following as elements, compounds, or mixtures. • Silver • pine tree • orange juice • oxygen • iced tea • air • water

24. Separating Mixtures • Filtration • Distillation • Crystallization • Chromatography

25. 1. Filtration • Filtration: a technique that uses a porous barrier to separate a solid from a liquid. • Separates heterogeneous mixtures of solids and liquids

26. Filtration

27. 2. Distillation • A separation technique that is based on differences in the boiling points of the substances involved • A mixture is heated until the substance with the lowest boiling point boils to a vapor that can then be condensed into a liquid and collected.

28. Distillation

29. 3. Crystallization • A separation technique that results in the formation of pure solid particles of a substance from a solution containing the dissolved substance. • ie. Rock candy

30. Crystallization

31. 4. Chromatography • A technique that separates the components of a mixture based on the tendency of each to travel across the surface of another material.

32. Chromatography

33. Physical Properties of Matter • Physical properties are characteristics that can be observed or measured without changing the sample’s composition • intensive properties: are independent of sample size. • ie. density, color, boiling point • extensive properties are dependent on the amount of material present. • ie. mass and volume

34. Physical Changes of Matter • Changes that alter a substance without changing its chemical composition • ie. Changes in physical state

35. Sublimation: solid to gas phase For example: Dry ice

36. Boiling: liquid to gas

37. How can you change the physical appearance without changing the state

38. Chemical Properties of Matter • Chemical properties are only observed in chemical reactions • Reactivity: the tendency of a substance to undergo a particular chemical reaction when exposed to an agent.

39. Examples • 2H2O reactivity to electric current→ 2H2(g) + O2(g) • H2O reactivity to alkali metals→ H2(g) [Cesium in water causes explosion] • Fe reactivity to O2 + H2O (fog)→ Fe2O3(rust) Iron Oxide (you leave your bike out in the fog and it rusts)

40. Rubidium,Cesium, & Francium in water • http://www.youtube.com/watch?v=jJGqC4vXBms

41. Chemical Change • A process that involves one or more substances changing into new substances

42. Reactants: the starting materials in a chemical reaction • Products:the newly formed substances from a chemical reaction

43. 4 Indicators of Chemical Change: (often accompany chemical change) • color change • precipitate formation • gas evolution • heat evolution or heat absorption

44. 2 Types of Reactions • Exothermic: Heat is released/given off during a chemical reaction • Endothermic: Heat is absorbed during the chemical reaction

45. DEMOS: Examples of Chemical Change

46. Gas Formation • Zn + 2 HCl → H2 (g) + ZnCl2

47. Color Change and Precipitate Formation • 2 KI + Pb(NO3)2→ 2 KNO3 + PbI2 (s) • http://www.youtube.com/watch?v=RE-dFN7U91M&feature=player_detailpage

48. Conservation of Mass • In a chemical reaction, matter is neither created nor destroyed, but it can change from one form to another. • Mass of Reactants= Mass of Products • → Material Balance

49. Conservation of Mass • From a lab experiment designed to separate water into hydrogen and oxygen, a student collected 10.0 g of hydrogen and 79.4 g of oxygen. How many grams of water were originally present?

50. Chemistry • is the study of the composition of substances and the changes they undergo. • In chemistry, a specific language is used when referring to elements.