HISTORY OF THE ATOM

1. HISTORY OF THE ATOM interactive lecture – kandace little

2. LET’S MAKE A FIRST WORD BASED ON WHAT WE KNOW

3. Aristotle THE BEGINNINGS • I’m going to take you back to 350 B.C….

4. … earth

5. … water

6. … fire

7. … air

8. … • Aristotle asks you: “Can you deny that these are the fundamental elements of the earth, Ruler?” • Your reply? • Alas, after deep thinking, you are convinced that this wise philosopher is correct. Aristotle has made observations about life and this is his THEORY to explain those observations.

9. Jumping to 300 A.D... GOLD Lead Tin

10. … • The alchemists are inspired by Aristotle’s ideas and are trying to turn cheap metals into GOLD! • The news article says that even though the Pope issued that no gold-making occurred, the gold business continued. • However, despite the alchemists efforts, they were unsuccessful in changing cheap metals into gold.

11. A little later on.. GOLD • John Dalton states the Atomic Theory BREAKING NEWS: NEW THEORY FOUND! -All matter is made of atoms. -Atoms of an element are identical. -Each element has different atoms. -Atoms of different elements combine in constant ratios to form compounds. -Atoms are rearranged in reactions. LAW OF CONSERVATION OF MASS John Dalton = new hero 2 p+ 2 n0 Boyle, Crookes, Becquerel, Thomson, Rutherford, Chadwick

12. Dalton’s “Billiard Ball” model • Atoms are solid and indivisible.

13. Thompson Plum Pudding model • Negative electrons in a positive framework To show this is a positive framework

14. The Rutherford Model • Atoms are mostly empty space. • Negativeelectronsorbitapositivenucleus.

15. Bohr-Rutherford Model • Putting all this together, we get Bohr-Rutherford diagrams that look like this: 2 p+ 2 n0 3 p+ 4 n0

16. LET’S MAKE A LAST WORD BASED ON WHAT WE KNOW NOW

17. References • Chalkbored found at www.chalkbored.com • History of Chemistry found at http://www.columbia.edu/itc/chemistry/chem-c2507/navbar/chemhist.html