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Period: 300 to
Atomic Model
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460
Democritus's Atomic Model
Democritus had an idea of atoms but in a void. Democritus Atomic theory explains the existence of atoms and also its features. -
Daltons Atomic Model
Dalton believed that:
1. All matter is composed of atoms
2. Atoms cannot be made or destroyed
3. All atoms of the same element are identical
4. Different elements have different types of atoms
5. Chemical reactions occur when atoms are rearranged
6. Compounds are formed from atoms of the constituent elements -
Michael Farady
Michael Faraday verified that electrical force helped together an atom. -
J. Plucker
Julius Plucker built one of the first gas discharge tubes also known as a Cathode ray tube. -
Crookes
He developed the Crookes tube and in it produced cathode rays for the first time. He also invented the radiometer and spinthariscope. -
William Conrad Roentgen
William discovered X-rays while using the cathode ray tube. He found that X-rays can travel through solid objects. -
Becquerel
A french physicist who found that rays coming from a uranium ore affected a photographic plate like X-rays did. The rays were not from an external source and were more powerful than those from a sample of pure uranium. His experiment led to the discovery of natural radiocativity. -
J.J Thomson
He discovered the Plum pudding model of the atom and he describes the atom as a slightly positive sphere with small electrons inside. -
Hantaro Nagaoka
He discovered a plantery model of the atom based on saturns rigs but this moel was incorrect. -
Robert Millikan
Discovered the charge of an electron with his oil drop experiment. -
Ernest Rutherford
Rutherford theorized that atoms have a small positive chard in a small nucleus. He tested this theory with the gold foil experiment and he came up with a new model. -
Niels Bohr
He believed that outer orbitals could hold more electrons than inner orbitals. He also suggested that the outer orbitals determine the atom's chemical property. -
Electron Cloud Model
Electrons do not have fixed orbitals but have quantum mechanical orbitals. They float in the orbitals and each orbital has a certain amount of energy. -
Cockcroft and Walton
They built an accelerator and bombarded lithium with protons to make alpha particles. -
Schrodinger
Saw electons as a continuous clouds and introduced wave mechanics as a mathmatical model of an atom. -
Enrico Fermi
He did the first controlled chain reaction releasing energy from the atom's nucleus.
