Hybridization, Geometry, and Orbital Theory

Vocabulary flashcards covering hybridization, molecular geometries, Valence Bond theory, Molecular Orbital theory, and orbital overlap concepts.

Valence Bond (VB) Theory

A bonding model in which covalent bonds are formed by the OVERLAP of two half-filled atomic orbitals (one electron each) or one filled and one empty atomic orbital between adjacent atoms.

Hybridization

The mathematical combination ('blending') of standard atomic orbitals on a single central atom to form degenerate hybrid atomic orbitals with specific directions and geometries.

Electron Group Geometry

The spatial arrangement of all electron groups (bonding pairs, lone pairs, or single electrons) around a central atom to space negative charges as far apart as possible.

Molecular Geometry

The spatial arrangement considering only the positions of the atoms in a molecule, distinct from the overall arrangement of electron groups.

$sp^3$ Hybrid Orbital

A hybrid orbital formed by combining one $s$ and three $p$ orbitals on an atom, producing four degenerate orbitals pointing toward tetrahedral vertices separated by $109.5^\frac{1}{2}\text{ or }109.5^\top$ ($109.5^\text{o}$) angles.

$sp^2$ Hybrid Orbital

A hybrid orbital formed by combining one $s$ and two $p$ orbitals on an atom, yielding three degenerate orbitals in a trigonal planar geometry separated by approximately $120^\text{o}$ angles.

$sp$ Hybrid Orbital

A hybrid orbital formed by combining one $s$ and one $p$ orbital on an atom, yielding two degenerate orbitals in a linear geometry separated by $180^\text{o}$ angles.

Sigma ($\sigma$) Bond

A covalent bond formed by orbital overlap directly between the nuclei of bound atoms along the internuclear axis, creating the molecular framework and connectivity.

Pi ($\pi$) Bond

A covalent bond formed by the side-by-side overlap of parallel unhybridized $p$ orbitals around the periphery of the internuclear axis.

Electron Group

A region of negative charge surrounding an atom in a Lewis diagram, defined as a lone pair, a single electron, a single bond, a double bond, or a triple bond.

Molecular Orbital (MO) Theory

A bonding theory where atomic orbitals from multiple atoms combine mathematically across a molecule to form delocalized bonding and antibonding molecular orbitals.

Bonding Molecular Orbital

A molecular orbital formed by constructive interference (addition of wavefunctions) with high electron probability density between nuclei, resulting in lower energy than parent atomic orbitals.

Antibonding Molecular Orbital

A molecular orbital formed by destructive interference (subtraction of wavefunctions) with reduced electron density along the internuclear axis, resulting in higher energy than parent atomic orbitals.

Constructive Interference

The combination of atomic orbitals with wavefunctions of the same sign, leading to increased electron density between atomic nuclei to yield a bonding molecular orbital.

Destructive Interference

The combination of atomic orbitals with wavefunctions of opposite signs, creating cancellation (a node) between nuclei to yield an antibonding molecular orbital.

Hybrid Orbital Summary Table

A reference table showing that 2 hybrid orbitals ($sp$) produce linear geometry ($180^\text{o}$), 3 hybrid orbitals ($sp^2$) produce trigonal planar geometry ($120^\text{o}$), and 4 hybrid orbitals ($sp^3$) produce tetrahedral geometry ($109.5^\text{o}$).

Double Bond Structure in Ethylene

A representation showing that ethylene's double bond consists of a $\sigma$ bond formed by overlapping C $sp^2$ hybrid orbitals and a $\pi$ bond formed by parallel side-by-side overlap of unhybridized $2p$ orbitals.

Common Bonding Patterns Table

A summary diagram showing valence electrons and common neutral, positively charged, and negatively charged bonding configurations for boron, carbon, nitrogen, oxygen, and halogens.

Molecular Orbital Energy Diagram for $\text{H}_2$

An energy diagram illustrating how two hydrogen $1s$ atomic orbitals combine to form a lower-energy bonding $\sigma_{1s}$ orbital and a higher-energy antibonding $\sigma^*_{1s}$ orbital.

Orbital Interference Diagram

A diagram demonstrating $1s - 1s$ destructive interference forming an antibonding molecular orbital ($\sigma^*_{1s}$) and $1s + 1s$ constructive interference forming a bonding molecular orbital ($\sigma_{1s}$).

Benzene Bonding Framework

A structural representation of benzene ($\text{C}_6\text{H}_6$) showing its hexagonal $\sigma$ bond framework of $sp^2$ hybridized carbon atoms alongside six unhybridized $2p$ orbitals used for delocalized $\pi$ bonding.

VB/MO Combo

An approach in organic chemistry that blends Valence Bond theory (two-atom localized overlap for the $\sigma$ framework) with Molecular Orbital theory (delocalized combinations for $\pi$ systems).