Phosphorus

Phosphorus is an element which forms 1 bond. Because of this, it appears in many molecules, often to "cap" bonds at the ends when a single bond is needed. It can be found in the Limido group, in which it is singly bonded to a Yttrium atom.

Phosphorus, due to its large, rounded symbol, often contributes a decent amount of steric hindrance to molecules it can be found in.