Question

The molecular geometry of ${\mathrm{SF}}_6$ is octahedral. What is the geometry of ${\mathrm{SF}}_4$(including lone pair(s) of electrons, if any)?

• A. Pyramidal
• B. Trigonal bipyramidal
• C. Tetrahedral
• D. Square planar

Answer 1

The correct option is B

Trigonal bipyramidal

Explanation for correct option:

B. Trigonal bipyramidal:

Lone pair electrons:

1. Lone pair electrons do not exchange places with another atom during the formation of a covalent bond.
2. Lone pairs are present in the outermost electron shell of atoms.

Trigonal bipyramidal:

1. Five electron pairs define the triangular bipyramid geometry.
2. The Lewis diagram for this example, ${\mathrm{SF}}_4$, places $\mathrm{S}$ in the middle with one free electron pair and four fluoride atoms attached.

3. The electron pair geometry is a trigonal bipyramid with four atoms and one lone pair.

4. See-saw is the name of molecular geometry.

Explanation for incorrect option:

A. Pyramidal:

1. A pyramidal in chemistry primarily refers to the molecular geometry, or to put it simply, the structure of compounds, including the lengths, angles, etc. of the bonds.
2. Trigonal pyramidal, a molecule with a pyramid-like form and a triangular base, is the phrase most frequently used when discussing pyramidal structures.

C. Tetrahedral:

When a molecule's core atom has four bonds and no lone pairs, the molecule is said to be tetrahedral.

D. Square planar:

1. The orbitals have an octahedral structure.
2. On opposing sides of the center atom, two orbitals each have a single pair of electrons.
3. The molecule has a square planar structure because the other four atoms are joined to the center atom.
4. Four bonds and two lone pairs on the central atom of the molecule provide the molecular form known as square planar.

Hence Option B. Trigonal bipyramidal is correct.