Chemistry Spl

Need to figure out if an atom is negative, positive, or neutral? Here's the formula for figuring out the formal charge of an atom:
Formal charge = [# of valence electrons] [electrons in lone pairs + 1/2 the number of bonding electrons]
This formula explicitly spells out the relationship between the number of bonding electrons and their relationship to how many are formally owned by the atom. However, since the number of bonding electrons divided by 2 terms is also equal to the number of bonds surrounding the atom, here's the shortcut formula:
Formal Charge = [# of valence electrons on atom] [non-bonded electrons + number of bonds].
Let us apply it to some examples. for example BH4 (top left corner).
The number of valence electrons for boron is 3.
The number of non-bonded electrons is zero.
The number of bonds around boron is 4.
So formal charge = 3 (0 + 4) = 3 4 = 1
The formal charge of B in BH4 is negative 1.
Lets apply it to :CH3 (one to the right from BH4)
The number of valence electrons for carbon is 4
The number of non-bonded electrons is two (it has a lone pair)
The number of bonds around carbon is 3.
So formal charge = 4 (2 +3) = 4 5 = 1
The formal charge of C in :CH3 is negative 1.
Same formal charge as BH4!
Lets do one last example. Lets do CH3 (with no lone pairs on carbon). Its the orange one on the bottom row.
The number of valence electrons for carbon is 4
The number of non-bonded electrons is zero
The number of bonds around carbon is 3.
So formal charge = 4 (0 +3) = 4 3 = +1
You can apply this formula to any atom you care to name.