Question

in the following diagrams, elements are represented by x and z, which form molecular compounds with one another. which diagram represents a molecule that has a bent molecular geometry? diagrams a: x:z: (with lone pairs), b: z:x:z (with lone pairs), c: :z:x:z: (with lone pairs), d: z=x=z (with lone pairs)

Explanation:

Step1: Recall Bent Geometry Conditions

Bent (angular) molecular geometry occurs in molecules with a central atom having 2 bonding pairs and 1 or 2 lone pairs (e.g., \( \text{H}_2\text{O} \): 2 bonds, 2 lone pairs; \( \text{SO}_2 \): 2 bonds, 1 lone pair). The central atom should have a steric number (bonding + lone pairs) of 3 or 4, with 2 bonding regions and lone pairs causing repulsion.

Step2: Analyze Each Option

• Option A: Structure is \( \text{X} - \text{Z} \) (1 bond) with Z having lone pairs. Central atom? If X is central, only 1 bond – not bent. If Z is central, 1 bond to X – not bent.
• Option B: Central atom X, bonded to two Z atoms (2 bonding pairs) and has 1 lone pair (from the dots below X). Steric number = 2 bonds + 1 lone pair = 3. This matches bent geometry (e.g., \( \text{SO}_2 \) has 2 bonds, 1 lone pair, bent).
• Option C: Central X, bonded to two Z atoms, each Z has lone pairs, but X has no lone pairs (all electrons in bonds). Steric number = 2 (linear geometry, like \( \text{CO}_2 \)).
• Option D: Central X, double - bonded to two Z atoms, no lone pairs on X. Linear geometry (steric number 2, linear).

Answer:

B. \( \boldsymbol{Z:\overset{..}{X}:Z} \)