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dalton: solid sphere model
An English chemist, John Dalton performed experiments with various chemicals that showed that matter, indeed, seem to consist of elementary lumpy particles (atoms). Although he did not know about their structure, he knew that the evidence pointed to something fundamental. -
thompson: plum pudding model
The English physicist J.J. Thomson discovered the electron and proposed a model for the structure of the atom. Thomson knew that electrons had a negative charge and thought that matter must have a positive charge. His model looked like raisins stuck on the surface of a lump of pudding. -
rutherford: nuclear model
Rutherford knew that atoms consist of a compact positively charged nucleus, around which circulate negative electrons at a relatively large distance. The nucleus occupies less than one thousand million millionth (10 ) of the atomic volume, but contains almost all of the atom's mass. If an atom had the size of the earth, the nucleus would have the size of a football stadium. -
bohr: bohr (planetary) model
A Danish physicist, Niels Bohr came up with a theory that said the electrons do not spiral into the nucleus and came up with some rules for what does happen.
RULE 1: Electrons can orbit only at certain allowed distances from the nucleus.
RULE 2: Atoms radiate energy when an electron jumps from a higher-energy orbit to a lower-energy orbit. Also, an atom absorbs energy when an electron gets boosted from a low-energy orbit to a high-energy orbit. -
rutherford: nuclear model
Rutherford finally identify the particles of the nucleus as discrete positive charges of matter. Using alpha particles as bullets, Rutherford knocked hydrogen nuclei out of atoms of six elements: boron, fluorine, sodium, aluminum, phosphorus, an nitrogen. He named them protons, from the Greek for 'first', for they consisted of the first identified building blocks of the nuclei of all elements. He found the protons mass at 1,836 times as great as the mass of the electron. -
schrodinger: quantum mechanics model
Erwin Schrödinger had an interesting idea: Why not go all the way with particle waves and try to form a model of the atom on that basis? His theory worked kind of like harmonic theory for a violin string except that the vibrations traveled in circles. The world of the atom, indeed, began to appear very strange. It proved difficult to form an accurate picture of an atom because nothing in our world really compares with it. The "psi" symbol came from the Greek lettering system. -
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