Molecular Orbital Builder

Molecular orbital (MO) theory is a method for determining molecular structure in which electrons are not assigned to individual bonds between atoms but are treated as moving under the influence of the nuclei in the whole molecule.

Key Concepts

When atomic orbitals combine to form molecular orbitals, they can combine in two fundamental ways:

• Constructive interference: When atomic orbitals combine in-phase (same sign wavefunctions), they form bonding orbitals with lower energy than the original atomic orbitals.
• Destructive interference: When atomic orbitals combine out-of-phase (opposite sign wavefunctions), they form antibonding orbitals with higher energy than the original atomic orbitals.

Types of Molecular Orbitals

• Sigma (σ) orbitals: Formed by head-on overlapping of atomic orbitals. The electron density is concentrated along the internuclear axis.
• Pi (π) orbitals: Formed by side-by-side overlapping of p orbitals. The electron density is distributed above and below the internuclear axis.
• Antibonding orbitals (σ*, π*): Have a node between the nuclei, resulting in decreased electron density between the atoms.
• Non-bonding orbitals: Do not contribute to bonding and typically maintain energy levels similar to their parent atomic orbitals.

The diagram below shows a simplified molecular orbital diagram for a diatomic molecule:

In this simulation, you can visualize these concepts by building molecular orbitals from atomic orbitals and observing how they combine to form bonding and antibonding configurations.