1. Chemistry for Changing Times 12 th Edition Hill and Kolb Chapter 2 Atoms: Are They for Real? John Singer Jackson Community College, Jackson, MI © 2010 Pearson Prentice Hall Inc.

2. © 2010 Pearson Prentice Hall, Inc. 2/2 Atoms: The Greek Idea ~384 B.C.E., Aristotle: All matter is composed of four elements and all matter is continuous, not atomistic.

3. © 2010 Pearson Prentice Hall, Inc. 2/3 Atoms: The Greek Idea ~ 450 B.C.E., Leucippus and Democritus Atomos: The point at which matter can no longer be subdivided.

4. © 2010 Pearson Prentice Hall, Inc. 2/4 Atoms: The Greek Idea Aristotle declared matter to be infinitely divisible.

5. © 2010 Pearson Prentice Hall, Inc. 2/5 Lavoisier: The Law of Conservation of Mass Early 1700s Lavoisier: Law of Conservation of Mass: During a chemical change, matter is neither created nor destroyed.

6. © 2010 Pearson Prentice Hall, Inc. 2/6 Lavoisier: The Law of Conservation of Mass

7. © 2010 Pearson Prentice Hall, Inc. 2/7 1799, Proust: Law of Definite Proportions: A compound always contains the same elements in certain definite proportions. Proust: The Law of Definite Proportions

8. © 2010 Pearson Prentice Hall, Inc. 2/8 Proust: The Law of Definite Proportions Regardless of the source, copper carbonate has the same composition.

9. © 2010 Pearson Prentice Hall, Inc. 2/9 Proust: The Law of Definite Proportions The Berzelius experiment illustrates the Law of Definite Proportions.

10. © 2010 Pearson Prentice Hall, Inc. 2/10 1803, John Dalton: Law of Multiple Proportions: Elements may combine in more than one set of proportions, with each set corresponding to a different compound. John Dalton and the Atomic Theory of Matter

11. © 2010 Pearson Prentice Hall, Inc. 2/11 John Dalton and the Atomic Theory of Matter

12. © 2010 Pearson Prentice Hall, Inc. 2/12 John Dalton and the Atomic Theory of Matter All matter is composed of extremely small particles called atoms. All atoms of a given element are alike and differ from the atoms of any other element. Compounds are formed when atoms of different elements combine in fixed proportions. A chemical reaction involves the rearrangement of atoms.

13. © 2010 Pearson Prentice Hall, Inc. 2/13 Out of Chaos: The Periodic Table 1869, Dmitri Mendeleev Mendeleev arranged the elements in order of increasing atomic mass. He left gaps for yet undiscovered elements. He also predicted the properties of those elements. When those elements were eventually discovered, many of his predictions were found to be accurate.

14. © 2010 Pearson Prentice Hall, Inc. 2/14 Out of Chaos: The Periodic Table

15. © 2010 Pearson Prentice Hall, Inc. 2/15 Out of Chaos: The Periodic Table

16. © 2010 Pearson Prentice Hall, Inc. 2/16 Atoms: Real and Relevant Atoms are a very real concept. It is even possible to observe computer-enhanced images of atoms.

17. © 2010 Pearson Prentice Hall, Inc. 2/17 Leucippus Revisited: Molecules Molecules are groups of atoms chemically bonded together. A molecule of water is composed of two atoms of hydrogen (H) bonded to an atom of oxygen (O). H 2 O