-
460 BCE
Democritus
Democritus he proposed that all matter, including space and time, was made up of small units named atoms. He did no experiment and had little evidence, but his idea was kept on by Lucretius. -
Dalton
-agreed that all matter was created by atoms, which he believed to be indestructible. He also stated that compounds are created by combining two atoms , and all atoms of given elements are identical in their mass and properties. -
Thompson
J.J. Thompson
- Discovered the electron.he experimented by testing and studying the nature of electric discharge in a high vacuum cathode-Ray tube. -
Rutherford
Ernest Rutherford
-Used the gold foil experiment to discover the modern model of an atom. He concluded that all positive charges were centralized, while negative electrons orbited the nucleus. -
Bohr
Neil's Bohr
- Explained that the outer orbit in an atom could hold more electrons than the inner orbits. By knowing this, one can determine the atoms chemical properties. He also started the idea that electrons emit light by jumping orbits.
