Which of the following correctly represents the Lewis dot structure for a neutral molecule of ammonia (NH_3)?

• A. A nitrogen atom with three double bonds to hydrogen atoms.
• B. A nitrogen atom with three single bonds to hydrogen atoms and one lone pair on nitrogen.
• C. A nitrogen atom with two single bonds to hydrogen atoms and two lone pairs on nitrogen.
• D. A nitrogen atom with three single bonds to hydrogen atoms and no lone pairs.

Answer: (B)

Verified step by step guidance

1. Recall that ammonia (NH_3) consists of one nitrogen atom bonded to three hydrogen atoms, and the molecule is neutral overall.
2. Determine the total number of valence electrons: nitrogen has 5 valence electrons, and each hydrogen has 1 valence electron, so total valence electrons = 5 + 3 \times 1 = 8 electrons.
3. Distribute electrons to form bonds: each hydrogen forms a single bond with nitrogen, using 2 electrons per bond, so 3 bonds use 6 electrons.
4. Assign the remaining electrons as lone pairs: after bonding, 8 - 6 = 2 electrons remain, which form one lone pair on the nitrogen atom.
5. Verify the octet rule for nitrogen: nitrogen has 3 single bonds (6 electrons) plus 1 lone pair (2 electrons), totaling 8 electrons, satisfying the octet rule.