History of the atom
- Created by: m.turner
- Created on: 16-05-18 19:53
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- History of the Atom
- 1st = Dalton
- Described the atoms as solid spheres. Said that different spheres made up different elements.
- 2nd = JJ Thompson
- Concluded that they weren't solid spheres. He showed that an atom must contain smaller, negatively charged particles (due to charge and mass) - electrons
- His theory = the plum pudding model - a ball of positive charge with electrons stuck in it.
- 3rd = Rutherford
- Conducted the alpha particle scattering experiment - fired positively charged alpha particles through thin gold foil
- Some particles passed straight through, some got slightly deflected and some got fired back = plum pudding could not be right.
- Came up with the idea of the nuclear model of the atom = a tiny, positively charged nucleus at centre, where most of the mass is concentrated.
- A cloud of negative electrons surrounds this nucleus - so most of the atom is empty space. Shown through being deflected when fired at the nucleus (showing there's positive charge)
- 4th = Bohr
- Scientists realised that the 'cloud' of negative would be attracted to the nucleus causing it to collapse.
- Bohr proposed that electrons orbit around the nucleus in shells - each shell is a fixed distance.
- Was supported by many experiments.
- Further Experiments
- Showed that the nucleus can be divided into smaller particles = have the same charge as a hydrogen nucleus
- JAMES CHAWICK = provided evidence of a neutral particle - neutron
- 1st = Dalton
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