1. 1 Chapter 2 Connections

2. 2 Alchemy Alchemy was in essence a philosophy – the idea that humans could strive and attain an ideal life via the conversion of “baser” metals into gold.

3. 3 The Discoverers Joseph Black (1756): Air is more than one gas. “Fixed air” turned limewater cloudy. Henry Cavendish (1766): “Inflammable air” – hydrogen gas. Daniel Rutherford (1772): “Noxious air”, supporting neither life nor combustion (nitrogen gas)

4. 4 The Discoverers: Oxygen Karl Scheele (Sweden, 1771): Things burned in this “fire air”. Joseph Priestley (England, 1774): Heated (now called) mercury(II) oxide, forming mercury and oxygen gas. Antoine Lavoisier (France 1770’s): Proper measurements; combustion is the reaction of fuel with oxygen in the air.

5. 5 Law of Conservation of Mass - Lavoisier Although matter might change its form during a chemical reaction, it cannot be created or destroyed – mass, and therefore matter, is conserved. (But keep in mind Einstein’s E = mc 2 !)

6. 6 Law of Conservation of Mass – An Example If 8.00 grams of hydrogen gas combine with 64.0 grams of oxygen gas, how many grams of the product, water, can be formed? hydrogen + oxygen —> water 8.00 g 64.0 g ?? g

7. 7 Law of Conservation of Mass – Solution hydrogen + oxygen —> water 72.0 g 8.00 g 64.0 g 72.0 g

8. 8 Law of Definite Proportions – Proust (1799) When substances come together to form compounds, they always do so in fixed proportions. If 8.00 g of hydrogen combines with 64.0 g of oxygen to form water, then 4.00 g of hydrogen will combine with ____ g of oxygen to form water???

9. 9 Law of Definite Proportions - Solution 32.0 g If 8.00 g of hydrogen combines with 64.0 g of oxygen to form water, then 4.00 g of hydrogen will combine with 32.0 g of oxygen to form water

10. 10 Law of Multiple Proportions - Dalton The same pair of elements can combine in different proportions to form compounds having very different properties. 64.0 g 8.00 g oxygen combines with 64.0 g hydrogen to form water. 128.0 g 8.00 g oxygen combines with 128.0 g hydrogen to form hydrogen peroxide.

11. 11 Dalton’s Atomic Theory All matter consists of atoms All atoms of one element are identical in mass and other properties and are different from atoms of any other element (Dalton didn’t know about isotopes). Atoms of one element cannot be converted into atoms of another elements (in a chemical reaction). Compounds are the chemical combination of 2 or more elements in a specific ratio.

12. 12 Dalton’s Elemental Symbols

13. 13 Chemical Formulas Summarize the elements present and their proportions in that compound. A compound with 1 carbon and 2 oxygens is CO 2. A compound with 6 carbons, 12 hydrogens and 6 oxygens is C 6 H 12 O 6.

14. 14 Polyatomic Ions

15. 15 Polyatomic Ions – An Example Write the formula of the compound containing 2 ammonium ions and 1 sulfide ion.

16. 16 Polyatomic Ions – Solution (NH 4 ) 2 S

17. 17

18. 18 Predictions Based on Patterns - Mendeleev

19. 19 Periodic Table Organization– Moseley’s X-ray Data (1914)

20. 20 Orbital E nergy Levels

21. 21 Atomic Number The Periodic Table – Organized by Atomic Number

22. 22 Groups The Periodic Table – Organized into Groups

23. 23 Periods The Periodic Table – Organized into Periods

24. 24 Metals, Non-metals and Metalloids The Periodic Table – Metals, Non-metals and Metalloids