Atomic structure
- Created by: Susan Rickett
- Created on: 17-04-18 14:09
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- Atomic structure
- Mass number: the number of protons + neutrons
- Current Atomic Model
- Nucleus contains protons and neutrons
- neutrons have no charge they have an atomic mass of 1
- protons are + they have an atomic mass of 1
- radius about 10^-10 m
- Nucleus surrounded by shells containing electrons
- Electrons are negative they have an atomic mass of 1/2000
- Nucleus contains protons and neutrons
- Isotopes
- Contain different number of neutrons
- Contain the same number of protons
- e.g. Carbon 12, Carbon 14
- Different forms of the same element
- Atomic number: the number of protons
- Development of the atom model
- The Greeks were the first to think that matter was made of particles
- 1804 John Dalton
- Each element was made of a different type of atom
- 1897 JJ Thomson
- Plum Pudding Model
- Discovered electrons
- 1909 Rutherford
- Alpha particle scattering experiment
- Most of the atom must be empty space because most alpha particles passed straight through the gold foil.
- The nucleus must be positively charged as alpha particles were repelled and deflected by large angles
- The nucleus must be very small as very few alpha particles were deflected back.
- Further developments
- Neils Bohr: electrons orbit at certain distances called energy levels
- Chadwick proved the existence of the neutron
- Alpha particle scattering experiment
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