Atomic structure Flashcards
What happened in 1804?
John dalton agreed with democtirtus that matter was made up of tiny spheres that couldn’t be broken up.
He reckoned that each element was made up of a different type of atom.
Nearly 100 years later what did J.J Thompson discover?
That electrons could be removed from atoms.
Daltons theory wasn’t quite right.
What did thompson suggest?
Atoms were spheres of positive charges with tiny negative electrons stuck in them like a plums pudding.
in 1909 what experimnet did marsden and rutherford do?
TRied firing a beam of alpha particles at thin gold foill.
Expected the positively charged alpha particles would be slightly defletced by the electroms in the plum pudding model.
However, what went on in the experiment>
Most alpha particles went through the odd one came straight back at them.
What did marsden and rutherfod rd realise>
Most of the mass of the atom was concentrated in a tiny nucleus .
The nucleus must have a large positive charge since it repelled positive alpha particles by large angles.
What did the experiment show about the atom?
It was just empty space .
What gives the atom its overall size?
The negtaove elctrons.
What is the radius of the atoms nucleus?
About 10,000 times smaller than the radius of the atom.
Mass of
proton
neutron
electron
1.
1.
1/2000.
charge of a
proton
neutron
electron
+1.
0.
-1.
aTOMS HAVE WHAT CHARGE
NO OVERALL CHARGE
