Chapter 19, Problem 19.130MP

(a)

Interpretation Introduction

Interpretation:

The electron dot structure for $\text{NO,}{\text{O}}_{\text{2}}{}^{\text{-}}\text{,}{\text{ONOO}}^{\text{-}}$ and the $\text{O-N-O}$ bond angle in ${\text{ONOO}}^{\text{-}}$ has to be given.

Concept introduction:

Electron-dot structure: It is a diagram in which dots are placed around the chemical symbol of an element to show its valence electrons. It is also called as Lewis dot diagrams.

• Lewis structures are diagrams that represent the chemical bonding of covalently bonded molecules and coordination compounds
• It is also known as Lewis dot structures which represent the bonding between atoms of a molecule and the lone pairs of electrons that may exist in the molecule.
• The Lewis structure is based on the concept of the octet rule so that the electrons shared in each atom should have 8 electrons in its outer shell.

VSEPR theory:

• Using VSEPR theory, the exact geometry of a molecule can be obtained.
• In VSEPR, the geometry of the molecule is explained based on minimizing electrostatic repulsion between the molecules’ valence electrons around a central atom
• Bond angle is the angle between two bonds of a molecule and it is determined based on the electron-domain geometry.

  [Bond angles: tetrahedral = $\text{109}{\text{.5}}^{\text{o}}$, trigonal planar = ${\text{120}}^{\text{o}}$, T-shape = ${\text{90}}^{\text{o}}$]

(b)

Interpretation Introduction

Interpretation:

The reason for having an intermediate bond length between the length of a $\text{NO}$ triple bond and a $\text{NO}$ double bond for $\text{NO}$ and its paramagnetic behaviour has to be accounted.

Concept introduction:

Molecular orbital theory:

• The atomic orbitals of the atoms constituted in a molecule are combined to produce new orbitals called Molecular Orbitals.
• Like atomic orbitals, a molecular orbital can accommodate maximum two electrons and the two electrons must have opposite spins (Pauli Exclusion Principle).
• The numbers of MO’s are equals to the number of atomic orbitals combined in such a way that the linear combination of similar atomic orbitals to form one bonding and one anti-bonding MO’s.
• The bonding MO’s are lower in energy than the anti-bonding MO’s.
• HOMO is the highest energized occupied orbital in the MO’s.
• Relative energy levels of molecules are according to the energy levels of atomic orbitals.
• LUMO is the lowest energized orbital in the MO’s.

Bond order:

$\text{Bond}\text{order}\text{=}\frac{\text{1}}{\text{2}}\left[\left(\begin{array}{l}\text{number}\text{of}\text{electrons}\text{in}\\ \text{bonding}\text{molecular}\text{orbitals}\end{array}\right)\text{-}\left(\begin{array}{l}\text{number}\text{of}\text{electrons}\text{in}\\ \text{antibonding}\text{molecular}\text{orbitals}\end{array}\right)\right]$

Paramagnetic property: The presence of unpaired electrons in the electronic configuration of the metal ion in coordination complex.

Diamagnetic property: The absence of unpaired electrons of the metal ion in coordination compound which do repel by the magnet.