developed in part by Ron Gillespie at McMaster in 1957, allows us to predict 3-D shape. 21 juin 2023 · Step 1: Find the total valence electrons in O2 molecule In order to find the total valence electrons in O2 (oxygen) molecule, first of all you should know the valence electrons present in a single oxygen atom. (Valence electrons are the electrons that are present in the outermost orbit of any atom.).