What is the molecular geometry of the ClO_2^- ion?

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

Answer: (B)

Verified step by step guidance

1. Step 1: Determine the total number of valence electrons in the ClO_2^- ion. Chlorine (Cl) has 7 valence electrons, each oxygen (O) has 6 valence electrons, and the negative charge adds 1 extra electron. So, total valence electrons = 7 + 2 \times 6 + 1.
2. Step 2: Draw the Lewis structure of ClO_2^- by placing chlorine as the central atom bonded to two oxygen atoms. Distribute the valence electrons to satisfy the octet rule for each atom, keeping in mind the extra electron from the negative charge.
3. Step 3: Count the number of electron domains (regions of electron density) around the central chlorine atom. These include bonding pairs (single or multiple bonds) and lone pairs of electrons.
4. Step 4: Use the VSEPR (Valence Shell Electron Pair Repulsion) theory to predict the molecular geometry. The shape depends on the number of bonding pairs and lone pairs around the central atom. Lone pairs repel more strongly and affect the shape.
5. Step 5: Since ClO_2^- has two bonding pairs and one lone pair on the central chlorine atom, the electron domain geometry is trigonal planar, but the molecular geometry (shape) is bent due to the lone pair causing a distortion.