John Baez - Mathematical Mysteries of the Periodic Table

Why do atoms behave the way they do?   Why do electrons form “shells,” as seen in the periodic table? 

Why does the first shell hold 2 electrons, the second 8, and the third 18: twice the square numbers 1, 4, and 9? 

It took many years to solve these mysteries, and a lot of detective work in chemistry, physics, and ultimately – once the relevant laws of physics were known – mathematics. 

Other mysteries remain unsolved, like the mass of the heaviest possible element. This talk will give a quick tour of these puzzles and some of the answers.