Organic Chemistry: Orbitals

Antibonding orbital  -  A molecular orbital that is higher in energy than its constituent atomic orbitals. Placement of electrons into such orbitals raises the total energy of the system, making bonding unfavorable.

Atomic orbital  -  An orbital that is associated with only one particular atom. This is in contrast to molecular orbitals, which are spread across a collection of atoms.

Bonding orbital  -  A molecular orbital that is lower in energy than its constituent atomic orbitals. Placement of electrons into such orbitals lowers the total energy of the system, making bonding favorable.

Bond order  -  The number of electron pairs involved in a covalent bond. In terms of Molecular Orbital theory, it is the number of bonding electron pairs minus the number of antibonding electron pairs. Larger bond order means greater bond strength and shorter bond length.

Covalent bond  -  Interaction between atoms held together by the sharing of electrons.

Delocalization  -  The phenomenon in which electrons are spread out over several atoms or bonds as opposed to being localized to specific atoms or bonds.

Electronegativity  -  The relative tendency for an atom to attract electrons to itself. Measured on an arbitrary scale of 4.0, with fluorine being the most electronegative element. Electronegativity increases from left to right across the periodic table and decreases as you move down a group.

Hybridization  -  The linear combination of atomic orbitals into hybrid orbitals that accommodate particular molecular geometries.

Hybrid orbital  -  Orbitals formed from the combination of atomic orbitals that accommodate particular geometries.

Lewis Dot structure  -  A common way to represent molecules, it uses lines to depict bonded electron pairs and dots to represent lone pairs. Inner shell electrons are not shown.

Molecular orbital  -  Orbitals that, in contrast to atomic orbitals, are distributed over an entire molecule instead of being localized to specific atoms.

Pi bond ( Π bond)  -  Covalent bond formed from the sideways overlap of two p -orbitals.

Sigma bond ( σ bond)  -  Covalent bond formed from the head-on overlap of two orbitals.

Valence bond theory  -  A theory of covalent bonding that treats bonds as the overlap of atomic orbitals. A simple extension of Lewis structures.

Valence Shell Electron Pair Repulsion  -  VSEPR for short. A model that predicts molecular geometry by minimizing repulsion between adjacent electron pairs.