Which of the following is the correct Lewis dot structure for a neutral molecule of NH_3?

• A. N atom with three single bonds to H atoms and one lone pair on N
• B. N atom with three single bonds to H atoms and one lone pair on each H atom
• C. N atom with two single bonds to H atoms, one double bond to H, and one lone pair on N
• D. N atom with three single bonds to H atoms and no lone pairs on N

Answer: (A)

Verified step by step guidance

1. Step 1: Determine the total number of valence electrons in the molecule. Nitrogen (N) has 5 valence electrons, and each hydrogen (H) has 1 valence electron. Since there are 3 hydrogens, total valence electrons = 5 + (3 × 1) = 8 electrons.
2. Step 2: Identify the central atom, which is nitrogen in NH_3, because it is less electronegative than hydrogen and can form multiple bonds.
3. Step 3: Connect each hydrogen atom to the nitrogen atom with a single bond. Each single bond represents 2 electrons, so 3 single bonds use 6 electrons.
4. Step 4: Distribute the remaining electrons as lone pairs on the central atom. After forming 3 single bonds (6 electrons), 2 electrons remain, which form one lone pair on nitrogen.
5. Step 5: Verify that each atom has a complete octet or duet. Hydrogen atoms have 2 electrons each (duet), and nitrogen has 3 bonds (6 electrons) plus 1 lone pair (2 electrons), totaling 8 electrons, satisfying the octet rule.