-
Democritus in 465 B.C. believed that matter could be devided smaller and smaller into little pieces that couldn't be divided any more. This was his view of the atom. The atom's only difference were in their size and shape.
-
Dalton said that all mass is made of atoms and atoms cannot be devided or destroyed. He also said that the mass of atoms in the same element were the same.
-
Ernest Rutherford's version of the atom disagreed with J.J. Thomson's plum pudding model of the atom. He proved that most of the atom is empty space and the nucleus is positively charged.
-
While doing experiments with photography, Becquerel discovered that some chemicals decompose and give off destructive rays.
-
Thomson's model is sometimes called a "plum pudding model" or a "raisin bread model." The Crooke's tube experiment showed Thomson that atoms contained electrons and also that electrons had a negative charge.
-
Marie Curie studied the rays of Becquerel's experiments and discovered that they weren't rays at all, but tiny particles. Marie Curie won the nobel prize for her experiments.
-
Millikan along with Harvey Fletcher did an oil drop experiment where they measured the charge of an electron.
-
Niels Bohr's model wasn't exactly correct but it was approximately correct. Borh said that the electrons in an atom orbit the nucleus. His model as known as the planetary model.
-
Of all the models, the Quantum model is the most recent. In this model the electrons surround the nucleus like in the Bohr model. The Quantum model also includes a nucleus containing protons and neutrons.
-
Chadwick discovered the neutron of the atom. He also confirmed that the atom contained a neutral particle. This had already been proposed by Ernest Riutherford.
-
In 384 B.C. Aristotle developed a theory that said all matter consisted of four basic elements, fire, air, water, and earth. The reason this was widely excepted was because Aristotle was one of the most respected philosophers of the time.
