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.
Upload the file in WordPress Dashboard and describe as below.
See following figure.