What is the electron geometry of the nitrite ion (NO_2^-)?

• A. Linear
• B. Tetrahedral
• C. Bent
• D. Trigonal planar

Answer: (D)

Verified step by step guidance

1. Step 1: Determine the Lewis structure of the nitrite ion (NO_2^-). Count the total valence electrons: Nitrogen has 5, each oxygen has 6, and there is an extra electron due to the negative charge, so total electrons = 5 + 2*6 + 1 = 18 electrons.
2. Step 2: Draw the skeletal structure with nitrogen as the central atom bonded to two oxygen atoms. Distribute the electrons to satisfy the octet rule for each atom, placing lone pairs on oxygen and possibly nitrogen.
3. Step 3: Identify the regions of electron density (bonding and lone pairs) around the central nitrogen atom. Count each bond and lone pair as one region of electron density.
4. Step 4: Use the VSEPR (Valence Shell Electron Pair Repulsion) theory to determine the electron geometry based on the number of electron density regions. For three regions, the electron geometry is trigonal planar.
5. Step 5: Confirm that the electron geometry is trigonal planar, which matches the correct answer, even though the molecular shape (considering only atoms) might be bent due to lone pairs.