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.