| what is the atomic theory? | the idea that all things were made from tiny particles that cant be broken down further and is separated from each other by an empty space. this proposed by a guy called democritus who was alive around 500 B.C |
| how did john Dalton describe atoms and when? | in1800s Dalton described atoms as solid spheres. he also suggested different types of spheres make up different elements |
| how did JJ Thomson describe the atom and when? | in 1897 JJ Thomson came up with the plum pudding model.
he did an experiment which showed atoms could not be solid spheres and instead they must have contained negatively charged particles which we now know as electrons. so the plum pudding model is a general ball of positive charge (the pudding) and electrons stuck in it (the plums) |
| what did ernest rutherford find out and when? | in 1909 Ernest took positively charged particles and fired it at a thin sheet of gold the idea was that if the positive charge in the atom was generally spread out as JJ Thomson proposed in the plum pudding model then the particles should go right through it because there would not be any concentrated positive charge to repel them. weirdly though some of the particles were deflected to the side some even bounced right back. this proved JJ theory wrong |
| what was rutherfords model? | rutherford came up with a nuclear model he proposed that instead of a field of a positive charge there was some sort of compact nucleus which contained all of the positive charges of the atom and he thought the negative charge existed in a sort of cloud around this central nucleus. but there some doubts on rutherfords model there didn't seem to be anything stopping this cloud of negative charge rushing in towards the positive nucleus meaning the atom should just automatically collapse wich we know it doesnt. |
