ch2 - history of chemistry (people)

John Dalton

• dalton’s atomic theory

• law of definite proportions

• law of multiple proportions

dalton’s atomic theory

• each element is composed of tiny indestructible particles called atoms

• all atoms of a given element have the same mass and other properties that distinguish them from atoms from other elements

• atoms combine in simple, whole-number ratios to form compounds

• atoms are neither created nor destroyed during chemical change

law of definite proportions

number of atoms of the elements always exist in the same ratio

law of multiple proportions

if 2 elements form 1 compound, the mass of one element reacts with the masses of other element in a ratio

JJ Thompson

• discovered the electron

• cathode ray tube

• observed the electron, which was less massive than atoms and was negatively charged

Robert A. Millikman

• oil drop experiment

• from the charge, you can get the mass of the electron

• oil droplets can be electrically charged

ernest rutherford

• positively charged alpha particles sent towards gold foil

• atoms must have a large amount of empty space and there must be small, heavy, positively charged nucleus at center of atom

• nucleus has proton