John dalton and his billiard ball model. - 1803

• All elements are made of atoms
• All atoms of the same element are alike, he doesn't believe in isotopes
• Atoms of elements combine to form compounds in simple ratios
• Chemical reactions happen when atoms are combined separated or rearranged

Jj tomson and plum pudding - 1904

• Each atom was a sphere filled with positively charged fluid with negative electrons scattered throughout
• Atoms are not indivisible but are made of smaller particles
• Woo electrons got discovered
• Cathode ray tube evidence: he noticed that electricity in a vacuum moved away from positive charges

Rutherford and the planetary model - 1911

• Rutherford fired positively charged alpha particles thru gold foil and discovered it mostly went through. He thus concluded atoms must be nearly all empty space. Additionally, deflected alpha radiation suggested a positive core to an atom, he called this a nucleus
• The positive particles inside were called protons

Niels bohr, energy level model - 1913

• Electrons orbit in fixed shells
• Dense positive nucleus
• Electrons jump from shells via gaining energy
• He reasoned this is how light absorption and emission come to be, with evidence being the emissions of a hydrogen atom.

James chadwick, idk chadwick atom model (he sucks at naming) - 1932

• He assaulted a sheet of beryllium with alpha particles, then other particles came loose, namely neutrons