What Is the Formal Charge on P in PBr3 and N in NBrI2

[wahaj]

Homework Statement

find formal charge on P in PBr₃ and N in NBrI₂

Homework Equations

Formal charge = number of valence electrons-number of lone pairs- 1/2 number of bonding electrons

The Attempt at a Solution

FC on P = 5 - 1 - 3 = 1
FC on N = 5 - 1 - 3 = 1

these are wrong for some reason and I can't figure out. I know I have the lewis diagram correct for these molecules(I checked)

 

[chemisttree]

How does the Lewis diagram help you here? I always calculated what I knew first and then balanced the molecule's charge by assigning the oxidation number of the unknown. In these examples, I would have assumed the halogens were -1 as you have and the P or N would have an equal but opposite charge.

 

[symbolipoint]

NBrI₂

Halides usually have charge of -1. The compound given is as neutral charge.
N, u
Br, -1
I, -1
I, -1
Total, 0.

Find u.

 

[Vineeth T]

Homework Statement

find formal charge on P in PBr₃ and N in NBrI₂

Homework Equations

Formal charge = number of valence electrons-number of electron pairs- 1/2 number of bonding electrons

The Attempt at a Solution

FC on P = 5 - 1 - 3 = 1
FC on N = 5 - 1 - 3 = 1

these are wrong for some reason and I can't figure out. I know I have the lewis diagram correct for these molecules(I checked)

The formal charges in both the cases is zero.
In your above formula for FC you wrote the second term as " number of electron pairs ",it should be " number of non-bonded electrons ".