Question

write the molecular geometry of tef₄. select one: a. trigonal bipyramidal b. trigonal pyramidal c. trigonal planar d. see saw

Explanation:

To determine the molecular geometry of \( \text{TeF}_4 \), we first find the steric number of the central Te atom. Te is in group 16, so it has 6 valence electrons. Each F atom contributes 1 valence electron, and there are 4 F atoms. The formula for steric number (SN) is \( \text{SN}=\text{number of bonding pairs}+\text{number of lone pairs} \). The number of bonding pairs is 4 (since there are 4 Te - F bonds). The number of lone pairs is calculated as \( \frac{6 - 4\times1}{2}=1 \). So the steric number is \( 4 + 1=5 \). The electron - pair geometry for a steric number of 5 is trigonal bipyramidal. When there is 1 lone pair and 4 bonding pairs in a trigonal bipyramidal electron - pair geometry, the molecular geometry is see - saw (also called distorted tetrahedron or sawhorse).

• Option A: Trigonal bipyramidal is the electron - pair geometry, not the molecular geometry (since there is a lone pair), so A is incorrect.
• Option B: Trigonal pyramidal has a steric number of 4 with 1 lone pair (e.g., \( \text{NH}_3 \)), but here the steric number is 5, so B is incorrect.
• Option C: Trigonal planar has a steric number of 3 (no lone pairs on the central atom, e.g., \( \text{BF}_3 \)), so C is incorrect.
• Option D: With a steric number of 5 (4 bonding pairs and 1 lone pair), the molecular geometry is see - saw, so D is correct.

Answer:

D. See Saw