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460
Democritus
- Greek
- 460 B.C.
- Believed that atoms were indivisble and indestructable
- Was a constituent part in the early stages of understanding atoms
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The Dalton Model
- atoms are indivisible and indestructable
- he associtaed chemical compounds through ratios
- developed atomic theory from Democritus' hypotheses
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John Dalton
- English school teacher and chemist
- proved Democritus' ideas via scientific theory
- studied ratios and produced "Dalton's Atmoic Theory"
- Law of Definite Proportions:
- Due to the fact that atoms combine in whole-number ratios, regardless of the chemical compound, masses of elements are always in the same proportion.
- Law of Multiple Proportions:
- When elements combine and produce more than one compound, their masses are set in to a whole number, fixed proportion.
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The Thomson Model
- British scientist J.J Thomson discovers negative electron
- believed atoms were composed of simply positive and negative charges whih were bound together by an attractive froce
- he uses a plum-pudding model to symbolise relationship between electrons and protons
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Nagaoka Model
- Japanese physicist Hantaro Nagaoka
- suspected the presence of a nucleus in an atom
- also suspected theat electrons move in orbits around nucleus
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The Rutherford Model
- After the gold-aplha particle experiment, Rutherford discovers the nucleus, a dense yet very small positive mass in the centre of the atom.
- Rutherford models thus consist of nuclei and wandering electrons
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The Bohr Model
- Austrain chemist Neils Bohr discovers electronic energy levels.
- Bohr, in other words, discovered that electrons circle the nucleus through an established orbital cycle whch consitst of energy levels.
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Electron Cloud Model
- Austrian mathmatician Erwin Schrodinger fabricates an equation to describe the electron orbitals Bohr had previously discovered
- Based his observations on probability and where the electron MIGHT be and where it MAY end up
- Used an electron cloud to express the probable locations an electron may be found
- the denser the cloud, the more probable the electron can be found
- similiarly, if the cloud is less dense, it is less probable the electron is in that location
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Neutron Model
- English physicst James Chadwick discovers neutrons, a subtamocui particle with no electric charge, however remain in a neutral state
- he also varifies that nuclei contain both protons and neutrons.
