1. Atomic Theory Label the 3 different particles that make up an atom
What is the charge of each?
Draw a model of the element Boron (B)

2. Development of atomic theory

3. Democritus
Atoms are indivisible, indestructible, fundamental units of matter.
“Atomos”
Never went further than this

4. Aristotle Four elements of air, earth, water and fire.
Regardless of the number of times you cut a form of matter, you would always have a smaller piece of that matter. 

5. Dalton’s Atomic Theory
1. All matter is composed of extremely small particles called atoms.
2. Atoms of given elements are identical in size, mass, and other properties.

6. Dalton’s Atomic Theory
3. Atoms can not be subdivided, created, or destroyed.
4. Atoms of different elements can combine in simple, whole-number ratios to form chemical compounds.

7. Dalton’s Atomic Theory
5. In a chemical reaction, atoms are combined, separated, or rearranged.
Example:
H2 + O2  H20

8. William Crookes Discovered cathode rays
Set the stage for JJ Thompson and his discoveries

9. J. J. Thomson
Discovery of the electron
Cathode ray tube

10. Positively charged ions, called cations, move towards the cathode
Negatively charged ions, called anions, move towards the anode.

11. J. J. Thomson’s Model

12. Robert Millikan - oil drop experiment
- calculated the mass of the electron

13. Ernest Rutherford Existence of the nucleus and its relative size
Gold foil experiment

14. Rutherford’s Gold Foil Experiment

15. Rutherford’s Gold Foil Experiment

16. James Chadwick Discovered the last known subatomic particle
The neutron which has no charge

17. No. Not this Neutron…
This neutron.