CPK
From Proteopedia
"CPK" stands for Corey-Pauling-Koltun. It commonly refers to a color scheme for the elements that originated in physical models developed by Corey, Pauling and Koltun. In this color scheme, carbon is gray or black, oxygen is red, nitrogen is blue, and hydrogen is white.
A color key such as the one below can be inserted into Proteopedia using existing templates (see Help:Color Keys): C H O N
