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 ".

 

[DeeNos]

As a scientist, it is important to always double-check your calculations and assumptions. In this case, it seems that the incorrect values for the formal charges may be due to a mistake in the number of valence electrons or the number of bonding electrons. It is important to carefully count and consider all electrons in the molecule, including any lone pairs and multiple bonds, in order to accurately determine the formal charge. It may also be helpful to use a periodic table to confirm the number of valence electrons for each atom. Additionally, it is important to remember that formal charge is a theoretical concept and may not always accurately reflect the true distribution of electrons in a molecule. It is always important to consider other factors, such as electronegativity and molecular geometry, when analyzing the properties of a molecule.