Question

In \( \text{NO}_3^- \) ion, the number of bond pairs and lone pairs of electrons on the nitrogen atom are:

• A. \( 2, 2 \)
• B. \( 3, 1 \)
• C. \( 1, 3 \)
• D. \( 4, 0 \)

Hint:

To determine the bonding in ions, count the pairs of electrons shared as bond pairs and the non-shared pairs as lone pairs.

Answer 1

The Correct Option is D

To determine the number of bond pairs and lone pairs of electrons on the nitrogen atom in the NO₃^- ion, we need to draw its Lewis structure.

1. Count the total number of valence electrons:

• Nitrogen (N) has 5 valence electrons.
• Oxygen (O) has 6 valence electrons each, and there are 3 oxygen atoms, so 3 * 6 = 18 valence electrons.
• The negative charge adds one more electron.
• Total valence electrons: 5 + 18 + 1 = 24 electrons.

2. Draw the skeletal structure:

Nitrogen is the central atom, and the three oxygen atoms are bonded to it.

3. Distribute the electrons:

The Lewis structure of NO₃^- shows that nitrogen forms three bonds with the oxygen atoms. One of the bonds is double, and the other two are single. The structure can be represented as:

O

||

O - N - O^-

4. Determine bond pairs and lone pairs:

• Nitrogen forms three bonds (one double bond and two single bonds). Therefore, there are 3 bond pairs.
• Nitrogen has no lone pairs of electrons.

Therefore, the number of bond pairs is 3, and the number of lone pairs is 0.

Final Answer: 3, 0

However, the given options do not contain 3,0. The closest answer is 4,0 if you are counting the double bond as two bond pairs. The correct answer should be 3,0. However, if we count the double bond as two bond pairs, then the answer is 4,0. Therefore ,option 4 is the most correct of the provided options.

The correct answer from the provided options is option 4: 4, 0.