how do i know if my formal charge is right?

Question

abb0t · Answer

If you did it right, then it's correct.

anonymous · Answer

sorry, let me rephrase my question, does my formal charge have to equal to the overall charge of a molecule?

abb0t · Answer

Yes. For example, if you have water, H$_2$O, you know it is H$^+$ (+1 charge) + OH$^-$ (-1 charge), each has a charge of +1 or -1, so to make water (neutral) = 0
You see how -1 + 1 = 0

abb0t · Answer

For calcium and chlorine, you know calcium carries a 2+ charge, and you know that chlorines has a -1 charge, that means you need TWO chlorines (-1 + -1 = -2) to give you a neutral CaCl$_2$ charge which is neutral.

anonymous · Answer

oh okay thank you!