Atomic structure

THE ATOM 

J.J Thomson - found out that electrons could be removed from the atom

He came to a conclusion  that the atom was a sphere of positive charge with tiny negative electrons stuck in them like plums in a plum pudding - this was called the plum pudding theory

However later on Rutherford and Marsden carried out an experiment where they fired alpha particles at thin gold foil. their prediction was that the alpha particles would be slightly deflected.However most of the alpha particles went straight through with the odd one coming back at them. They came to the conclusion that most of the mass was located in the centre in a nucleus and the rest of the atom was mainly empty space. The nucleus had an overall positive charge as it repelled the positive protons  that were fired at it. This is called the nuclear model 

particle         mass               charge

proton              1                     +1

neutron            1                      0

electron         1/2000                -1

the atom

Atoms have no overall charge

Electrons have the same charge as a proton but opposite

Hence they have the same number of protons and neutrons which give it an overall…