Atomic Structure Flashcards
What did John Dalton decide about matter in 1804?
Matter was made up of tiny spheres (atoms) that couldn’t be broken up and that each element was made of a different type of atom
What was J J Thomson’s discovery that proved John Dalton’s theory on matter was wrong?
He discovered that electrons could be removed from atoms. This proved Dalton’s theory, that atoms couldn’t be broken up, wasn’t right.
What was J J Thomson’s “Plum Pudding” theory?
Atoms were spheres of positive charge with tiny negative electrons stuck in them like plums in a plum pudding.
Describe what happened with the gold foil experiment.
A beam of alpha particles were fired at thin gold foil. Most alpha particles went straight through and were picked up by a detector on the other side but some came straight back.
What did Rutherford and Marsden conclude from their gold foil experiment?
Most of the mass of an atom was concentrated at the centre in a positively charged nucleus since some of the positively charged alpha particles were repelled. The rest is just empty space.
What are the relative charges and masses of protons, neutrons and electrons?
Protons: mass = 1 and charge = +1
Neutrons: mass = 1 and charge = 0
Electron: mass = 0 and charge = -1
