Constructing lewis electron structures. Determine the total number of valence electrons in the molecule or ion. Add together the valence electrons. Webfor the brf 2 lewis structure there are a total of 21 valence electrons. If you check the formal charges for brf 2 you will find that each atom has a formal charge of zero. Webmay 1, 2024 · lewis structures, proposed by gilbert n. Lewis, provide a visual representation of electron arrangements in molecules. They depict valence electrons as.