Chapter 9: Molecular Geometry and Bonding Theories

Lewis Structure

A diagram that shows the bonding and lone pairs in a molecule but does not denote its shape.

Bond Angles

The angle formed between two bonds around a central atom that determines the molecular shape.

Valence Shell Electron Pair Repulsion (VSEPR) Theory

A model that predicts the shape of molecules based on the repulsion between electron pairs.

Electron Domains

Regions of space around a central atom where electrons are most likely to be found. Includes lone pairs and bonds.

Trigonal Planar Geometry

The geometry of a molecule with three bonding electron domains and no lone pairs, resulting in bond angles of 120°.

Tetrahedral Geometry

The geometry of a molecule with four bonding pairs of electrons, resulting in bond angles of approximately 109.5°.

Polar Covalent Bonds

Bonds where electrons are shared unequally between atoms, resulting in a dipole moment.

Hybridization

The process of combining different atomic orbitals to create new orbitals of equal energy.

Sigma (σ) Bond

A single bond formed by head-to-head overlap of orbitals, characterized by cylindrical symmetry around the bond axis.

Pi (π) Bond

A bond formed by sideways overlap of orbitals, found in double and triple bonds.

Localized Electrons

Electrons that are confined to a specific bond between two atoms.

Delocalized Electrons

Electrons that are spread out over several atoms, contributing to resonance structures.

Octahedral Geometry

The geometry of a molecule with six electron domains and bond angles of 90°.

Seesaw Geometry

A molecular geometry resulting from four bonds and one lone pair, leading to bond angles less than 120° and less than 90°.

Nonbonding Pairs

Electron pairs that are not involved in bonding and can affect molecular shape by occupying more space than bonding pairs.

Electron Domain Geometry

The three-dimensional arrangement of electron domains around a central atom.

Trigonal Bipyramidal Geometry

The geometry of a molecule with five electron domains, having bond angles of 120° and 90°.

Hybrid Orbitals

Orbitals formed by mixing different types of atomic orbitals to accommodate bonding requirements in molecules.