C1.5
- Created by: mayaholdstock
- Created on: 23-07-17 14:13
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- C1.5 History of the atom
- Ancient Greeks were first to have ideas about atoms
- In early 1800's Dalton linked his ideas to strong experimental evidence
- His idea was tiny, hard spheres that couldn't be divided or split
- At end of 1800s Thomson discovered a tiny negatively charged particle called the electron
- Thomson proposed the 'plum pudding' model for the atom
- 10 years later Geiger and Marsden fired an alpha particle at very thin sheet of gold foil, a few particles repelled showing there was a small positive charge in the middle
- In the nuclear model, electrons orbit around a nucleus
- The nucleus contained positively charged atoms
- Bohr then found out that the the electrons were orbiting in energy levels (shells)
- In 1932 Chadwick proved that there are uncharged particles called neutrons in the nucleus
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