VSEPR Theory and Molecular Geometry: Key Concepts in Chemistry

Valence Shell Electron Pair Repulsion (VSEPR) theory

A model used to predict the geometry of molecules based on the repulsion between electron groups around a central atom.

Electron groups

A lone pair, single bond, double bond, triple bond, or single electron on a central atom.

Electron group geometry

The arrangement of electron groups around a central atom.

Molecular geometry

The arrangement of atoms in a molecule, considering only the positions of the nuclei.

Linear geometry

An electron or molecular geometry with two electron groups and a bond angle of 180°.

Trigonal planar geometry

An electron or molecular geometry with three electron groups and bond angles of 120°.

Tetrahedral geometry

An electron or molecular geometry with four electron groups and bond angles of 109.5°.

Trigonal bipyramidal geometry

An electron geometry with five electron groups, featuring axial and equatorial positions.

Octahedral geometry

An electron geometry with six electron groups and bond angles of 90°.

Trigonal pyramidal shape

A molecular geometry with three bonding groups and one lone pair.

Bent shape

A molecular geometry with two bonding groups and two lone pairs.

Seesaw geometry

A molecular geometry with four bonding groups and one lone pair in a trigonal bipyramidal arrangement.

T-shaped geometry

A molecular geometry with three bonding groups and two lone pairs in a trigonal bipyramidal arrangement.

Square pyramidal geometry

A molecular geometry with five bonding groups and one lone pair in an octahedral arrangement.

Square planar geometry

A molecular geometry with four bonding groups and two lone pairs in an octahedral arrangement.

Net dipole moment

The overall dipole moment of a molecule, resulting from the vector sum of individual bond dipoles.

Molecular polarity

The property of a molecule having an uneven distribution of electron density, leading to a net dipole.

Hybridization

The mixing of atomic orbitals to form new hybrid orbitals that are used in bonding.

Sigma (σ) bond

A covalent bond formed by the end-to-end overlap of orbitals along the bond axis.

Pi (π) bond

A covalent bond formed by the side-to-side overlap of parallel p orbitals.

sp³ hybridization

Hybridization involving one s and three p orbitals, resulting in tetrahedral geometry.

sp² hybridization

Hybridization involving one s and two p orbitals, resulting in trigonal planar geometry.

sp hybridization

Hybridization involving one s and one p orbital, resulting in linear geometry.

sp³d hybridization

Hybridization involving one s, three p, and one d orbital, resulting in trigonal bipyramidal geometry.

sp³d² hybridization

Hybridization involving one s, three p, and two d orbitals, resulting in octahedral geometry.

Molecular orbital (MO) theory

A theory that describes bonding in terms of molecular orbitals that are delocalized over the entire molecule.

Linear Combination of Atomic Orbitals (LCAO)

A method of constructing molecular orbitals by combining atomic orbitals.

Bonding molecular orbital

A molecular orbital lower in energy than the atomic orbitals from which it is formed, stabilizing the molecule.

Antibonding molecular orbital

A molecular orbital higher in energy than the atomic orbitals from which it is formed, destabilizing the molecule.

Bond order

A measure of bond strength, calculated as half the difference between the number of electrons in bonding and antibonding orbitals.