What is the product of one equivalent of phosphorus and three equivalents of hydrogen? What does its Lewis Structure look like?

The product is called phosphine, and it has a Lewis diagram similar to that of ammonia. The diagram shows a single pair of electron shared between each hydrogen molecule and the phosphorus molecule. One electron is from the hydrogen while the other is from phosphorus.

Because phosphorus has 5 valence shell electrons, the remaining two electrons exist as a lone pair. Using this information, the Lewis structure of phosphine can be imagined and drawn.