Question

Calculate the formal charge on each non-hydrogen atom in eachof the following molecules (show your work)

i know the answer but can someone tell me how to get to the answer?

1) H2C=N=N(2 dots on top and on side)
2. H2C-N(3 bonds)C(2dots)

Answer 1

Draw the Lewis structure. Apparently you have that. I must not have read your description correctly for I think you should have 18 electrons and I count only 16 from your post.
You should have, for a neutral molecule,
H = 1e
H = 1e
C = 6e
N = 5e
N = 5e
total e = 18.
I count 2 for CH bond.
2 for the other CH bond.
4 for left double bond on N.
4 for right double bond on N.
4 long pairs (2 on top and 2 on side of rightmost N).
Total 16 used. Where are the other two? or does the molecule have a -2 charge?

Answer 2

How to draw a lewis Dot structure for LiCl