Hybridization, Orbital Overlap, and Bonding Theories

Vocabulary practice flashcards covering bonding theories, orbital overlap (sigma and pi bonds), and the formation and geometry of sp3, sp2, and sp hybrid orbitals.

Covalent Bonds

The buildup of electron density between atoms.

Lewis Structures

Two-dimensional ($2D$) representations that show the locations of bonding and non-bonding electrons.

VSEPR Theory

A theory addressing the three-dimensional ($3D$) spatial distribution of electrons.

Valence Bond Theory

A theory stating that covalent bonds are formed by the overlap of orbitals between atoms, where electrons reside in orbitals centered on the atom from which they originate.

Molecular Orbital Theory (MO Theory)

A theory stating that covalent bonds are formed when atomic orbitals combine to form delocalized molecular orbitals.

Sigma ($\sigma$) Bonds

Bonds formed by the head-on overlap of orbitals where electron density is along the internuclear axis, creating increased electron density between the nuclei.

Pi ($\pi$) Bonds

Bonds resulting from the side-to-side overlap of orbitals with electron density located above and below the internuclear axis and a node along the axis; they cannot exist without a sigma ($\sigma$) bond.

Electron Promotion

The step in hybridization where an electron from a paired $2s$ orbital is moved into an empty $2p$ orbital to produce half-filled valence orbitals available for bonding.

Hybrid Orbital Formation

The combining or mixing of atomic orbitals to produce a set of degenerate orbitals; this specific orbital mixing step involves no change in energy.

$sp^3$ Hybrid Orbitals

Four degenerate hybrid orbitals formed by combining one $s$ orbital and three $p$ orbitals ($(1 \times s) + (3 \times p) = 4 \times sp^3$), each being $1/4\,s$ and $3/4\,p$ character and separated by $109.5^\circ$ in molecules with a steric number of $SN = 4$.

$sp^2$ Hybrid Orbitals

Three degenerate hybrid orbitals formed by combining one $s$ orbital and two $p$ orbitals ($(1 \times s) + (2 \times p) = 3 \times sp^2$), oriented at $120^\circ$ in a trigonal planar geometry for molecules with a steric number of $SN = 3$.

Unhybridized p Orbital ($sp^2$ Hybridization)

The single remaining $p$ orbital that is perpendicular ($90^\circ$) to the plane formed by the three $sp^2$ hybrid orbitals.

$sp$ Hybrid Orbitals

Two degenerate hybrid orbitals formed by combining one $s$ orbital and one $p$ orbital ($(1 \times s) + (1 \times p) = 2 \times sp$), arranged at $180^\circ$ in a linear geometry for molecules with a steric number of $SN = 2$.

Unhybridized p Orbitals ($sp$ Hybridization)

The two remaining $p$ orbitals that are perpendicular to each other and perpendicular to the axis of the two $sp$ hybrid orbitals.