So, how do people know so much about Atoms? Well, it’s all thanks to a few very important scientists. Dalton was the first scientists to propose that all matter is composed of atoms. He described atoms as being “tiny marbles”. The next big discovery about the atom came with Lavoisier. Lavoisier said that matter is conserved in all chemical reactions, so people cannot destroy matter. He also proved the Phlogiston theory, because of Joseph Priestley’s discovery of oxygen. The next big scientist to contribute in the discovery of the atom was Proust. He created the Law of Definite proportions, which sates that each compound has it’s own defined ratio of elements regardless of masses. One scientist who discovered mounds of information about the atom was Thomson. He said that atoms contain negatively charged particles, and these particles must be surrounded by oppositely charged particles. He also determined the mass to charge ratio of an electron. Wow! This led to Milikan determining the charge of an electron, therefore determining the mass.
One of the biggest discoveries of the atom, was made by Rutherford. During one of his experiments, he came to the surprising conclusion that inside a atom there is a nucleus. Thus, he changed the previous model (done by Thomson) and created a new one. In this model the atom is mostly space, with a dense, positive nucleus in the middle. Finally, with the discovery of the nucleus, Chadwick was able to fill in the final piece of the puzzle. He discovered neutrons- particles with no charge inside the nucleus. Everything we know today about atoms, such as protons, neutrons, atomic mass, charge, and how the atom looks, is all thanks to the work of these scientists.