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Democritus Theory
He thought that all matter is composed of tiny indestructible units, called atoms. he thought atoms in liquids were round and smooth,and solids were rough and prickly. -
Daltons theroy
All elements are composed of atoms. All atoms of the same element have the same mass, and atoms of different elements have different masses. Compounds contain atoms of more than one element. In a particular compound, atoms of different elements always combine in the same way. -
Nagaoka Planetary Model
Nagaoka's model said the stability came from rings like the ones of Saturn. The model made two predictions: 1) a very massive nucleus with electrons revolving around the nucleus. 2) This was bound by electrostatic forces like gravity. -
Thompson's Gold Foil
He said that electrons were in a cloud around the nucleus -
Rutherford's Discovery
He proved that most of an atom's mass was in the center (nucleus) of an atom. This was different from Thompson's. -
Chadwick Discovers Neutron
Chadwick discovered that there were smaller particles in the nucleus of an atom. These he called neutrons.
