Help with chem - Figuring out bond angles

[masochist]

This was a 2 part question.

Part i

Draw the 2 possible Lewis structures of N3H.

Part ii

Predict the N-N-N and H-N-N bond angles in each case and give your reasoning.

This is the answer scheme:

I successfully drew them both but I don't understand the bond angles part.

Firstly for the N-N-N one i don't get why it is 180 because there is a lone pair on the first N? do you disregard lone pairs if they're not on the centre atom?

Also for I N-N-H i don't understand why there are THREE charge centres? There does not appear to be any a lone pair on the centre N of N-N-H?..

[Tilia]

Yes, you only consider the central atom. For the second question, remember that lone pairs and bonds are negative charge centrews, so as it has 2 bonds and 1 lonepair, it has three negative charge centres.