To find the formal charges on nitrogen (N) and the starred oxygen (O) in a given molecule, we follow these steps:
1. Determine the number of valence electrons for each atom:
- Nitrogen (N) has 5 valence electrons.
- Oxygen (O) has 6 valence electrons.
2. Identify the bonding and non-bonding electrons around each atom:
- Bonding electrons are those involved in covalent bonds.
- Non-bonding electrons (also called lone pairs) are those not involved in bonding and are just on a single atom.
3. Use the formula for formal charge:
[tex]\[
\text{Formal charge} = (\text{Valence electrons}) - (\text{Non-bonding electrons}) - \left(\frac{\text{Bonding electrons}}{2}\right)
\][/tex]
### Calculation for Nitrogen (N):
If nitrogen is forming four covalent bonds (as in a structure like NH4+):
- Valence electrons for nitrogen (N) = 5
- Non-bonding electrons on nitrogen = 0 (since all electrons are involved in bonding)
- Bonding electrons on nitrogen = 8 (4 bonds, each bond has 2 electrons)
[tex]\[
\text{Formal charge on N} = 5 - 0 - \left(\frac{8}{2}\right) = 5 - 0 - 4 = +1
\][/tex]
### Calculation for the starred Oxygen (O):
If the starred oxygen is forming one covalent bond and has three lone pairs (like in a structure with an -O- connection):
- Valence electrons for oxygen (O) = 6
- Non-bonding electrons on oxygen = 6 (3 lone pairs * 2 electrons each)
- Bonding electrons on oxygen = 2 (1 bond, bond has 2 electrons)
[tex]\[
\text{Formal charge on O} = 6 - 6 - \left(\frac{2}{2}\right) = 6 - 6 - 1 = -1
\][/tex]
Based on these calculations, the formal charges are:
- Nitrogen (N): +1
- Starred Oxygen (O): -1
So, the correct answer is:
[tex]\[
N=+1, O=-1
\][/tex]
