Why is cyanide ion negatively charged?

The cyanide is 
A carbon atom has 4 valance electrons and nitrogen has 5. Below is a Lewis-dot-structure of cyanide.
:N≡C.
The carbon atom is still one electron short of having a full octet and so it will seize another electron from almost anything, making the cyanide ion negative and whatever it took the electron from it now positive.

True, the standard unit for volume is liters which can be represented by either a lower case "l" or a capital "l"