Chemistry 401

Intermediate Inorganic Chemistry

University of Rhode Island

Homework 1

1. (20 pts) Find the electron configuration (using rare gas notation for filled shells) and ground state term symbol for: Ru2+; Ce3+; Al; and W3+.

Answer

Ru2+: [Kr]4d6; L = 2 + 2 + 1 + 0 + –1 + –2 = 2 and S = ½ + –½ + ½ + ½ + ½ + ½ = 2 so the terms symbol is 5D

Ce3+: [Xe]4f1; L = 3 and S = ½ so the terms symbol is 2F

Al: [Ne]3s23p1; L = 1 and S = ½ so the terms symbol is 2P

W3+: [Xe]4f145d3; L = 2 + 1 + 0 = 3 and S = ½ + ½ + ½ = 3/2 so the terms symbol is 4F

2. (30 pts) Give the Lewis structure, formal charge and oxidation number for each atom, the likely σ-bond hybrid on the central atom, the molecular structure, and indicate all of the bond angles for: ReO4–; XeF4; and AlCl63–

Answer

ReO4–

Lewis structure:

Formal charges: Re, 0; O, –¼

Oxidation numbers: Re, +7; O, –2

Hybrid: sd3

Molecular structure: tetrahedral

Bond angles: all O-Re-O are ~109.5°

XeF4

Lewis structure:

Formal charges: Xe, 0; F, 0

Oxidation numbers: Xe, +4; F, –1

Hybrid: sp3d2

Molecular structure: square planar

Bond angles: F-Xe-F are either 90° or 180°

AlCl63–

Lewis structure:

Formal charges: Al, –3; Cl, 0

Oxidation numbers: Al, +3; Cl, –1

Hybrid: sp3d2

Molecular structure: octahedral

Bond angles: Cl-Al-Cl are either 90° or 180°