protactinium. protactinium. pa. not common, huh? these are natural transmutations. there are artificial transmutations, transmutations that are induced. and one of the first that we have recorded is that which a fellow by the name of ernest therford made in, i think, 1919. and all rutherford did was he-- what did he do? he had some nitrogen gas in a container and he put inside a piece of uranium--or was it radium? i don't know--that was emitting alpha particles. and then he found the nitrogen gas later on contained trace amounts of oxygen. and what was happening was the-- the alpha particle coming out, hitting the nitrogen gas and boom, making the gas turn from one element to another. and that's where there was a nuclear interaction. and let me draw that or let me write that interaction on the board. he had nitrogen, which is atomic number 7, got as many neutrons as nitrogen 14. you're breathi that all the ti, gang. it doesn't do anything for you. takes up space, give you the pressure in your lungs, yh? but when an alpha particle-- boom, bams into that, e followg wa