0.1 discovering the atom

John Dalton, 1800s

Elements combine in the same fixed ratio. Atoms are little sphere that can’t broke down any further

J.J. Thomson, 1897

Sealed a glass tuber with electricity and put a magnet near it see the ray bending. Concluded that something inside the atoms are negatively charges so it is not sphere. Disovered electrons

Robert Milikan 1909

Oil drop experiment found that electrons weighed 0 amu. Ignore electrons in atom’s mass bc they weigh nothing

Ernest Ruthford 1911

Gold Foil experiment: Shot a positively charged through a gold foil expecting it to wobble. It went through while few bounced back bc of the model of an actual particle. Discovered nucleus and electron clouds

James Chadwick 1932

Discovered neutrons, isotopes, and ions