Question

1. Determine the electron-domain geometry and molecular geometry for each of the following.

a. SBr2
b. PI4+
c. IBr2−

2. The following three compounds all have the same general formula, XF4. Compare the electron-domain geometries of these three compounds and explain what characteristic(s) of the central atom causes differences in geometry.

a. SiF4:
b. SeF4:
c. XeF4:

Answer 1

SBr2: Electron geometry-tetrahedral; molecular geometry-trigonal pyramidal

PI4+: Electron geometry-tetrahedral; molecular geometry-tetrahedral

IBr2−: Electron geometry- Trigonal bipyramidal ; molecular geometry- linear

Step-by-step explanation:

In SBr2, the molecule is of the structure type AX2E2 hence it is based on a tetrahedron but have two lone pairs of electrons hence the molecular geometry is trigonal pyramidal.

PI4+ has four electron domains and all of them are bond pairs hence both electron geometry and molecular geometry are both tetrahedral.

IBr2- is of the structure type AX2E3 hence it is based on a trigonal bipyramd and has a linear molecular geometry.

2)

SiF4 has a tetrahedral molecular and electron domain geometry because the central atom(Si) has no lone pairs.

SeF4 has a trigonal bipyramidal electron geometry with the structure AX4E. Its molecular geometry is See-saw since it has one lone pair of electrons that causes a deviation from its ideal trigonal bypyramidal geometry.

XeF4 has an octahedral electron domain geometry and the molecule is AX4E2. The two lone pairs are positioned above and below the plane of a square hence the molecule is square planar.