Valence Bond and Molecular Orbital Theory

Gen Chem 1: Lecture 5

What does Valence Bond Theory describe about covalent bonds?

It describes a covalent bond as the overlap of half-filled atomic orbitals that yield a pair of electrons shared between the two bonded atoms.

What are the two conditions that must be met for a covalent bond to form according to Valence Bond Theory?

An orbital on one atom overlaps an orbital on a second atom, and the single electrons in each orbital combine to form an electron pair.

What is the significance of orbital overlap in forming covalent bonds?

The mutual attraction between the negatively charged electron pair and the positively charged nuclei of the atoms serves to physically link the two atoms through a covalent bond.

How does the overlap of s and p orbitals produce sigma bonds?

Sigma bonds are produced by head-to-head overlap of orbitals, which can include the overlap of two s orbitals, s and p orbitals, or the end-to-end overlap of two p orbitals.

What characterizes a pi (π) bond?

A π bond results from the side-by-side overlap of two p orbitals.

What is dipole moment, and how is it calculated?

Dipole moment (µ) is calculated as the product of the charge (Q) and distance (d), expressed as µ = Q × d.

What is the concept of hybridization in chemistry?

Hybridization is the process of combining atomic orbitals to form new hybrid orbitals that can describe the bonding properties of molecules.

How does VSEPR theory relate to hybrid orbitals?

VSEPR theory predicts the shapes of molecules based on the arrangement of electron pairs, which informs the types of hybrid orbitals that will form.

What are the characteristics of bonding and antibonding molecular orbitals?

Bonding molecular orbitals are formed from constructive interactions between atomic orbitals, while antibonding molecular orbitals result from destructive interactions, characterized by a nodal plane.

Why does the O2 molecule display paramagnetic properties?

Because the two electrons in O2 occupy degenerate π* orbitals and are unpaired, making oxygen a biradical.