[:O triple bond C single bond N (3 pairs electrons)]
What are the formal charges on these atoms?
With which formula can the formal charge be calculated?
To find out a formal charge we have to " separate " the bonds so that every atom get one electron of it. Then we must know the number of valence electrons of the free atom and the number of electrons in the lone pairs ( 2 per lone pair ).
In case of :O triple bond C - N (3 pairs electrons) we get:
Explanation is given by use of data from periodic table of the elements. The mathematical formula to calculate it is also given.