Chapter 14, Problem 14.113P

(a)

Interpretation Introduction

Interpretation:

Lewis structure of ${\text{CO, CN}}^{-}{\text{, and C}}_2^{2-}$ has to be determined.

Concept-Introduction:

Lewis structure:

Electron dot structure also known as Lewis dot structure represents the number of valence electrons of an atom or constituent atoms bonded in a molecule.  Each dot corresponds to one electron.

(b)

Interpretation Introduction

Interpretation:

MO diagrams of ${\text{CO, CN}}^{-}{\text{, and C}}_2^{2-}$  has to be drawn and also its bond order and electron configuration has to be determined.

Concept-Introduction:

Molecular orbital (MO) theory:  It is a method for determining molecular structure in which electrons are not assigned to individual bonds between atoms, but are treated as moving under the influence of the nuclei in the whole molecule.

According to this theory there are two types of orbitals,

1. (1) Bonding orbitals
2. (2) Antibonding orbitals

Electrons in molecules are filled in accordance with the energy; the anti-bonding orbital has more energy than the bonding orbitals.

The electronic configuration of oxygen molecule $O_2$ can be represented as follows,

    ${\left({\text{σ}}_{\text{1s}}\right)}^2{\left({\text{σ*}}_{\text{1s}}\right)}^2{\left({\text{σ}}_{\text{2s}}\right)}^2{\left({\text{σ*}}_{\text{2s}}\right)}^2{\left({\text{σ}}_{\text{2p}}\right)}^2{\left( {\pi }_{\text{2p}}\right)}^4{\left( \pi {*}_{\text{2p}}\right)}^2$

The * represent the antibonding orbital

Orbital diagram represents each orbital with a box, with orbital’s in the same subshell in connected boxes, electrons are shown as arrows in the boxes, pointing up or down to indicate their spins.

Bond order: It is the measure of number of electron pairs shared between two atoms.

$\text{Bond}\text{order}\text{=}\frac{\text{1}}{\text{2}}\left(\begin{array}{l}\text{Number}\text{of}\text{electrons}\text{in}\text{bondoing}\text{MOs-}\\ \text{Number}\text{of}\text{electrons}\text{in}\text{antibonding}\text{MOs}\end{array}\right)$

Bond length is inversely proportional to the bond order.

If two or more different chemical species having same number of valence electrons are known as isoelectronic species.