Question

In a hypothetical molecule, a Nitrogen has two sets of lone pair electrons and two covalent bonds. What would its formal charge be?

Options:
(A) -2
(B) -1
(C) 0
(D) +1

Answer 1

The formal charge of a hypothetical Nitrogen with two lone pairs and two covalent bonds is calculated using the rule: Valence electrons - non-bonding electrons - 1/2(bonding electrons), resulting in a formal charge of -1.

Step-by-step explanation:

The student is asking about the formal charge of a hypothetical Nitrogen atom with two sets of lone pair electrons and two covalent bonds. To calculate the formal charge of an atom in a molecule, one can use the formula:

Formal Charge = (Valence electrons in free atom) - (Non-bonding electrons) - 1/2(Bonding electrons)

In this case, Nitrogen (which is in group 15 and therefore has 5 valence electrons) would have:

• 4 non-bonding electrons (two lone pairs)
• 4 bonding electrons (since it's involved in two covalent bonds)

Plugging these values into the formula gives us:

Formal Charge = 5 - 4 - 1/2(4) = 5 - 4 - 2 = -1

Therefore, the Nitrogen atom would have a formal charge of -1 (Option B).

Answer 2

The formal charge of a nitrogen atom in a hypothetical molecule with two sets of lone pair electrons and two covalent bonds is calculated to be -1, making (B) the correct answer.

Step-by-step explanation:

To determine the formal charge of a nitrogen atom in a hypothetical molecule with two lone pairs and two covalent bonds, we use the formula for formal charge:

Formal Charge = (Valence electrons of the atom) - (Lone pair electrons + ½ Bonding electrons)

Nitrogen normally has five valence electrons. In this hypothetical molecule, the nitrogen has two sets of lone pair electrons (4 electrons) and is participating in two covalent bonds (2 bonding electrons, or 4 bonding electrons if you count both electrons in the bonds). Using the formal charge formula:

Formal Charge of N = 5 - (4 + ½(4))
Formal Charge of N = 5 - (4 + 2)
Formal Charge of N = 5 - 6
Formal Charge of N = -1

Therefore, the formal charge of the nitrogen atom in this hypothetical molecule would be -1, making option (B) the correct answer.