atomic history scientists

democritus

first idea of a basic indivisible particle

democritus

called these particles atoms from the greek word atoms

dalton

first atomic theory

dalton

all matter composed of small particles called atoms

dalton

atoms are indivisble

dalton

atoms of a given element are identical

dalton

atoms are not created or destroyed in chemical reactions, just rearranged

dalton

atoms can combine is simple whole number ratios to form chemical compounds

dalton

accepted because it was able to explain laws and predict future results

JJ thomson

used cathode ray tubes

JJ thomson

discovered 1st subatomic particle (particle carried negative charge, named the particle the electron, showed electrons were a part of all elements)

JJ thomson

calculated the charge/mass ratio of an electron

JJ thomson

plum pudding model

millikan

oil drop experiment

millikan

determined electrons carried smallest possible negative charge

millikan

calculated the charge and the mass of an electron

rutherford

gold foil experiment

rutherford

discovered the nucleus of the atom (small dense positively charged center, atom was mainly empty space, most atoms mass was in the nucleus)

bohr

1st to propose electrons had fixed energy

bohr

electrons travel in concentric circles around the nucleus

bohr

planetary model

schrodinger

proposed treating electrons as waves

schrodinger

electrons traveled around nucleus in ever changing paths creating a region called an electron cloud

schrodinger

model based on mathematics

schrodinger

electron cloud/wave mechanical model

schrodinger

currently accepted model