1. Section 2.1 The History of Chemistry

2. Ideas About the Composition of Matter
The idea that all matter is made up of particles started with Greek Philosopher more than 2500 years ago.
How many times can you break down a substance until it cant be broken down any more?

3. Democritus
atomos = “uncuttable” The smallest particle that cannot be broken down any more Each material is made up of different types of matter

4. Aristotle Earth Air Fire Water
He supported a different hypothesis, everything is made up of four elements…
Earth
Air
Fire
Water

5. Alchemy
Part magician part scientist

6. Alchemists tried to turn lead to gold

7. Modern Chemistry

8. Daltons Theory Each element is made of an atom.
Atoms of one element are identical.
These atoms all the same mass.
No two elements have atoms with the same mass.
Billiard ball model  atoms are like tiny solid spheres.

9. Adding electrons…

10. J.J Thompson discovered the electron.
The raisin bun model

11. Rutherford’s planetary model (1907)
nucleus (+)
electron (-)

12. The atom is made up of mostly SPACE

13. Chadwick nucleus (+) containing protons (+) and neutrons (=)
electron (-)

14. Bohr Model (1922) Electron Shells

15. Quantum Mechanical Model – todays model

16. Which model of the atom will we use?
nucleus
protons (+) neutrons (=)
electron (-)