1. Slide 1 of 25 © Copyright Pearson Prentice Hall Your first lab report is due on Monday. Write down at least three questions you have about how to do it and we’ll discuss them briefly before beginning today’s lecture. DO NOW…

2. Slide 2 of 25 © Copyright Pearson Prentice Hall TIPS FOR LAB REPORTS Include all relevant sections listed on the lab report format reference sheet. Make sure your data table has units. Show one sample calculation for each type of calculation. Write a proper conclusion!

3. © Copyright Pearson Prentice Hall Elements and Compounds > Slide 3 of 25 Distinguishing Elements and Compounds How are elements and compounds different? 2.3 3

4. Slide 4 of 25 © Copyright Pearson Prentice Hall > Elements and Compounds Distinguishing Elements and Compounds Element -- the simplest form of matter that has a unique set of properties. (All of them are listed on the periodic table!) Ex: carbon, helium, barium, nitrogen, zirconium, phosphorus… 2.3

5. Slide 5 of 25 © Copyright Pearson Prentice Hall > Elements and Compounds A PURE ELEMENT CONTAINS ONLY ONE TYPE OF ATOM CERTAIN PURE ELEMENTS DO CONTAIN MOLECULES ( DIATOMIC MOLECULES ) When found by themselves, they are ALWAYS in pairs EX: H-H and O-O

6. Slide 6 of 25 © Copyright Pearson Prentice Hall > Elements and Compounds Crazy Uncle HOFBrINCl Hydrogen, Oxygen, Fluorine, Bromine, Iodine, Nitrogen, Chlorine

7. Slide 7 of 25 © Copyright Pearson Prentice Hall > Elements and Compounds Distinguishing Elements and Compounds Compound -- a substance that contains two or more elements chemically combined in a fixed proportion. Ex: magnesium oxide (MgO), water (H 2 O), sodium chloride (NaCl) … 2.3

8. Slide 8 of 25 © Copyright Pearson Prentice Hall > Elements and Compounds Distinguishing Elements and Compounds Breaking Down Compounds Compounds can be broken down into simpler substances by chemical means, but elements cannot. Ex: When sugar is heated, it goes through a chemical change. 2.3

9. Slide 9 of 25 © Copyright Pearson Prentice Hall > Elements and Compounds Distinguishing Elements and Compounds Final products carbon and water vapor 2.3 C 12 H 22 O 11 C H 2 O

10. Slide 10 of 25 © Copyright Pearson Prentice Hall Distinguishing Elements and Compounds Properties of Compounds In general, the properties of compounds are quite different from those of their component elements. EX: When the elements sodium and chlorine combine chemically to form sodium chloride, there is a change in composition and a change in properties. 2.3

11. Slide 11 of 25 © Copyright Pearson Prentice Hall > Elements and Compounds Distinguishing Elements and Compounds Chlorine is used to kill harmful organisms in swimming pools. 2.3

12. Slide 12 of 25 © Copyright Pearson Prentice Hall > Elements and Compounds Distinguishing Elements and Compounds Sodium is stored under oil to keep it from reacting with oxygen or water vapor in the air. Sodium vapor produces the light in some street lamps. 2.3

13. Slide 13 of 25 © Copyright Pearson Prentice Hall > Elements and Compounds Distinguishing Elements and Compounds Sodium Chloride (commonly known as table salt) is used to season or preserve food. 2.3

14. © Copyright Pearson Prentice Hall Elements and Compounds > Slide 14 of 25 Distinguishing Substances and Mixtures 2.3 Substances vs. Mixtures How can substances and mixtures be distinguished?  If the composition of a material is fixed, the material is a substance.  If the composition of a material may vary, the material is a mixture.

15. © Copyright Pearson Prentice Hall Slide 15 of 25 Elements and Compounds > Distinguishing Substances and Mixtures 2.3

16. © Copyright Pearson Prentice Hall Slide 16 of 25 Elements and Compounds > CLASSIFY as Pure Substance( element ), Pure Substance( compound ) Homogeneous Mixture, or Heterogeneous Mixture: 1.Gasoline 2.A stream with gravel at bottom 3.Air 4.Brass 5.Copper metal 6.Pure Apple Juice 7.Table salt 8.Chocolate Chip Cookies

17. © Copyright Pearson Prentice Hall Slide 17 of 25 2.3 Section Quiz 1.Passing an electric current through a certain substance produces oxygen and sulfur. This substance cannot be a(n) a.compound. b.mixture. c.element. d.solution.

18. © Copyright Pearson Prentice Hall Slide 18 of 25 2.3 Section Quiz 2.Which of the following is a mixture? a.sodium chloride b.carbon dioxide c.sucrose d.air

19. © Copyright Pearson Prentice Hall Elements and Compounds > Slide 19 of 25 Symbols and Formulas What do chemists use to represent elements and compounds? SYMBOLS!! You’ll start memorizing some next week 2.3 3

20. © Copyright Pearson Prentice Hall Slide 20 of 25 Elements and Compounds > ???