-
460 BCE
Democritus
Democritus was a Greek philosopher who hypothesized that atoms move all the time, are invisible, differ in shape, size, and temperature, and cannot be destroyed. -
John Dalton
John Dalton was an English chemist who hypothesized that all matter is made of atoms and atoms are invisible and indestructible. -
JJ Thomson
JJ Thomson discovered the electron and he used plum pudding. He proposed that the dough contained the positive charge and the raisins represented the negative electrons. Thomson’s model failed to recognize the positive charges as particles. -
Ernest Rutherford
Ernest Rutherford was a former student of JJ Thomson who proved his plum pudding model theory incorrect. Rutherford experimented with alpha particles and solid substances, such as gold foil. At the end of his experiment he concluded that the atom has a small-positively charged thing in the middle called a nucleus and a negatively charged cloud around it. Ernest Rutherford helped us have a better understanding of the atom. -
Neils Bohr
Bohr proposed that electrons move around the nucleus only in prescribed orbits. -
Erwin Schrödinger
Erwin Schrödinger was an Austrian physicist. He took Bohr's method a step farther. His theory was known as the quantum mechanical model of the atom. He formulated a wave equation that accurately calculated the energy levels of electrons in atoms. -
James Chadwick
He was an English physicist who was awarded the 1935 Nobel Prize in Physics for his discovery of the neutron in 1932.He discovered the existence of the neutron. He interpreted that particles being composed with a neutral electrical charge and the approximate mass of a proton. He later came to the conclusion thta this was the neutron
