A molecule doesn’t have “valence” electrons, although it can have non-bonding electron pairs, if that is what you mean.
First count the total electrons:
2*4 [for the 2 carbons] + 6*1 [for the 6 hydrogens] + 6 [for the sulfur]
= 20 total electrons. still with me?
you have to figure out, generally, what it is going to look like. It seems that sulfur would be the central atom, with the 2 CH3 groups attached to it. Since the H-C bonds have to be single (because of H, and because room has to be left for the bond to S), and because that also means that the S-C bonds have to be single, the molecule have all single bonds.
with 2 lone pairs of electrons put on the S.
and yep it looks like everyone has an octet (and H has a duet, 2 electrons, because it is special :)). If you count up the electrons, it should come out to 20, which it does. (the bonds count for two electrons, so 8*2+4=20).
hope I helped.Source(s): AP Chemistry, just went over Lewis structures in excruciating detail. 🙂
0. Chemical Compound = (CH3)2S
1. Count the number of valence electrons in your chemical compound.
V.E. = 2(4) [Carbon] + 2(3) [Hydrogen] + 1(6) [Sulfur] = 20
2. Our chemical compound tells us that there are two CH3 molecules attached to one Sulfur element.
You draw your Sulfur and connect a Carbon on its left and its right. Then you connect 3 Hydrogens to each Carbon.
You used 16 VE or [ 8 Bonds x 2 VE ]. Thus you currently have 4 remaining or [ (20 – 16) VE ].
You know that Hydrogen only requires 2 Electrons to be happy and Sulfur is our most electronegative element. Thus, you place the remain 4 VE on Sulfur.