Thales:Thales was a Greek philosopher who lived around 624 BC to 546 BC. He was the first Greek to attempt to find an explanation of the substance and existence of the world without relation to mythology. Thales' Theorem was if A, B, and C are parts on a circle where the line AC is the diameter of the circle then ABC is a right angle.
Democritus: Democritus was a Greek philosopher like Thales but lived from 460 BC to 370 BC. His mentor was Leucippus. Their understanding of atomic structure resembles the 19th century's understanding. Democritus is known as "the father of modern science". Democritus took a plastic bottle and decided that it was made up of small plastic parts that were "uncuttable". He named the parts "atomos" which means uncuttable in Latin.
Dalton: John Dalton was a scientist who lived around the 1800's. He is most known for his research on the atomic theory and on color blindness. He came up with the "pool ball" model. He also made "The Law of Multiple Proportions" which states when a chemical combination exists it does so in a ratio of small numbers. He also thought,like Democritus, atoms could not be divided.
JJ Thomson: JJ Thomson lived around 1897. He discovered negatively charged particles were in an atom which meant there had to be positively charged particles in the atom as well. He came up with the "berry muffin model".
Rutherford: Rutherford was Thomson's student but just a few years later, in 1911, he proved what his teacher taught him to be wrong. Thomson conducted the "gold foil experiment". He shot a beam of atoms at gold foil,if his teacher was right the atoms would have gone straight through the foil but they actually just bounced off in different directions. He discovered atoms had a nucleus made up of positively charged particles. He also figured out most of the atom's mass as in the nucleus and he made the "peach pit model".
Niels Bohr: Neils Bohr was a student of both Thomson and Rutherford and just two years later, in 1913, he discovered that electrons orbit the nucleus and he made the "onion model".
James Chadwick: In 1932 Chadwick discovered neutrons, neutrally charged particles, in the nucleus. His model had a nucleus with both neutrons and protons, and orbiting electrons around that.
Shroedinger: Shroedinger emphasized the need to think about where we can find electrons rather than how they move. Electron orbits were replaced by orbitals. His model contained a small nucleus and a cloud of where electrons could be.
Sources:1= in class lectures
2= wikipedia http://www.wikipedia.org/
