It’s usual to use WP LaTex in order to describe mathematical formula in WordPress. It’s common to use ChemDraw to describe molecular model in local PC, but I couldn’t find WordPress plug-in to describe them.
The query is “WordPress”, “chemical structure”, “plugin”. The result was Chemicalize for first, but it wasn’t found in official WordPress plug-in. Then I found JSmol2wp, and installed.
JSmol2wp express .pdb file. For example, you can find ATP (Wikipedia) and the .pdb file in link of DrugBank. Select all, copy and paste to text editor i.e. TeraPad. Save the file as “ATP.pdb”.
Upload the file in WordPress Dashboard and describe as below.
See following figure.