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

  • Thread starter Thread starter wahaj
  • Start date Start date
  • Tags Tags
    Atoms Charge
Click For Summary

Discussion Overview

The discussion revolves around calculating the formal charges on phosphorus in PBr3 and nitrogen in NBrI2. Participants explore the application of the formal charge formula and the relevance of Lewis diagrams in determining these charges.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Technical explanation

Main Points Raised

  • One participant presents a calculation for the formal charges on P and N, arriving at a formal charge of 1 for both, but expresses uncertainty about the correctness of this result.
  • Another participant questions the utility of the Lewis diagram in this context and suggests an alternative method of balancing charges using oxidation numbers.
  • A third participant provides a breakdown of the charges for the halides in NBrI2, indicating that the total charge must equal zero and proposes finding the unknown charge (u) for nitrogen.
  • A later reply reiterates the initial calculations for formal charges but corrects a terminology error in the formula, suggesting that "number of electron pairs" should be "number of non-bonded electrons" and asserts that the formal charges should actually be zero.

Areas of Agreement / Disagreement

Participants express differing views on the correct formal charges, with some calculations leading to a charge of 1 while another participant claims the formal charges should be zero. The discussion remains unresolved regarding the correct formal charges for both molecules.

Contextual Notes

There is a noted confusion regarding the terminology used in the formal charge formula, which may affect the calculations. Additionally, the assumptions about the charge states of the halogens and the overall neutrality of the compounds are not fully explored.

wahaj
Messages
154
Reaction score
2

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)
 
Physics news on Phys.org
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.
 
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.
 
wahaj said:

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 ".
 

Similar threads

Chemistry All possible resonance structures for SO4 2-
  • · Replies 9 ·
Replies
9
Views
14K
Chemistry How do we know ##BF_3## has Lewis structure but ##Al_2S_3## does not?
  • · Replies 1 ·
Replies
1
Views
2K
How to calculate formal charge in Nitrite Ion?
  • · Replies 2 ·
Replies
2
Views
3K
Chemistry Why Does IF5 Exhibit a Square Pyramidal Shape Despite Exceeding the Octet Rule?
  • · Replies 1 ·
Replies
1
Views
3K
Chemistry Acidity of H2O vs H2S: Formal Charge vs Electronegativity
  • · Replies 18 ·
Replies
18
Views
3K
Chemistry How to understand this acidic oxide chemical reaction?
  • · Replies 3 ·
Replies
3
Views
2K
Chemistry How to understand hybridization in ##CH_3NNN##?
  • · Replies 4 ·
Replies
4
Views
3K
How Do You Draw Correct Resonance Structures for H3CHCHC=NH?
  • · Replies 1 ·
Replies
1
Views
2K
Effective Charge on Valence Electrons of Sb
  • · Replies 1 ·
Replies
1
Views
2K
How to calculate protons and electrons in NH3BF3?
  • · Replies 26 ·
Replies
26
Views
7K