is this the strutual formula for

hydrogen cyanide
H:C:::N

and is this correct for cyanogen
:N:::C:C:::N

any advice woulds be appreciated

This is more chemistry than physics. It is important to put the subject line carefully in order for the right people to look at the problem. For HCN you are missing two electrons on the right side of the N. Same thing for the right N on NCCN. Count the electrons. H has 1, C has 4 and N has 5 for a total of 10. You show only 8 on HCN. For (CN)2, there are 4 for C and 5 for N for 9 and that times 2 = 18. You show 16.

oh ok i will amend it thank you im doing a combined science course so its a bit of everything unfortunately

No problem! It's great that you're taking a combined science course – that way, you'll get exposure to various scientific subjects. If you have any other questions in the future, feel free to ask!