How do you find the number of valence electrons in a molecule? Do I need to use the Lewis structure diagram to find out? Please help! I need to the total number of valence electrons for SiH4, H2SO4, CCl4, BF3 and I don't know how!

Answer 1

I have never used the term "valence electrons" for anything other than for atoms. Never for molecules; however, I suspect you are to count the electrons in the Lewis dot structure. Here is a site that explains how to draw Lewis structures. Post again with specific questions if you still need help.
http://misterguch.brinkster.net/lewisstructures.html