Atomic Isotopes

The man who tried to fake an element
BobbyBroccoli

This is a long video, over an hour, but it's pretty good. It combines a clear, basic explanation of atomic elements and isotopes with a history of 20th century research into nuclear physics and the events and politics of the time. It's kind of a lot to take in, so you might want to take a break in the middle.

2d Chart of atomic isotopes here.