Essential Element of the Day thread

This one;

Phosphorus

The one my dog is named for.

Phosphorus and an integral part of a healthy living system. But seriously this is one of the big ones right? Please discuss? Oh mighty forum?

And sorry I have absolutely no Idea where to stick this one; But humans are resources right? I mean their whole departments for that sort of thing out in the "real world".

Oh shinny,

This one is a compound.

http://en.wikipedia.org/wiki/Potassium_nitrate