p1.1 - the particle model

name the models of the atom in order from oldest to newest

dalton

jj thomson / plum pudding

rutherford

bohr

what are 3 features of the dalton model

atoms are small indestructible spheres

all the atoms in an element are the same

atoms of different elements are different

what 2 ideas did thomson have

atoms have an overall neutral charge

atoms contain negatively charged electrons

what is the plum pudding model

a positively charged mass with negatively charged electrons embedded in it

describe the gold foil experiment

positively charged alpha particles were fired at a thin piece of gold foil

most went straight through, some of which were partially deflected and a few were repelled

what conclusion did rutherford come up with following the gold foil experiment

most of the atom must be empty space (as most alpha particles went straight through)

there must be a tiny positively charged nucleus (as some were deflected and some fully bounced back)

what is the rutherford model

tiny positively charged nucleus containing most of the atom’s mass

electrons on the outside

what was the problem with rutherfords model

electrons would spiral inwards till they hit the nucleus

what is the bohr model

electrons move in fixed orbits around the nucleus called shells

the nucleus is made up of protons and neutrons

what is the average size of an atom

1 × 10^-10 m