VSEPR and Bond Hybridization

VSEPR Theory

Valence Shell Electron Pair Repulsion (VSEPR) theory asserts that the shape of a molecule is determined by the repulsion between electron pairs in its valence shell.
The goal of the theory is to minimise these repulsions to achieve the most stable configurations for molecules.
Molecular geometries such as linear, trigonal planar, tetrahedral, trigonal bipyramidal, or octahedral can be predicted using this theory.
The geometry of the molecule can impact its polarity, reactivity, phase of matter, colour, magnetism, and biological activity.

An important aspect of the VSEPR theory is the consideration of both lone pairs and bond pairs of electrons in the outer shell of each atom.
Lone pairs cause more repulsion than bond pairs due to their closer proximity to the central atom.
The presence of lone pairs can distort the shape of the molecule from the idealized shape predicted when all the electron pairs are bond pairs.

Bond hybridisation is the concept of mixing atomic orbitals to form new hybrid orbitals. It occurs in molecules where the central atom exhibits sp, sp2 or sp3 hybridisation.
These hybrid orbitals have different shapes and energy levels than the atomic orbitals, which helps explain the unique bonding characteristics of certain atoms.
This theory is useful to describe the covalent bonds in many organic molecules like methane (CH4), ethene (C2H4) and ethyne (C2H2).
Hybridisation links the concepts of molecular geometry (VSEPR theory) and orbital models for bonding.
However, hybridisation is not able to account for the properties of all molecules, such as those containing d-orbitals or those which violate the octet rule.