Chapter 14: Covalent Bonding: Orbitals

Vocabulary flashcards covering Molecular Orbital Theory, Valence-Bond Theory, orbital hybridization, and covalent bond formation based on Chapter 14 lecture slides.

Molecular Orbital (MO) Theory

A theoretical model used for the quantitative prediction of molecular properties—such as precise bond lengths, bond angles, and bond energy—by considering molecular orbitals delocalized over the molecule.

Molecular Orbitals (MOs)

Orbitals formed as linear combinations of atomic orbitals that are delocalized over two or more atoms, rather than remaining isolated on individual atoms.

Constructive Interference (MO Theory)

The additive combination of atomic wavefunctions (e.g., \text{\textPsi}_{\text{\textsigma}} = \text{\textpsi}_{1s\text{A}} + \text{\textpsi}_{1s\text{B}}) that yields a bonding molecular orbital with increased electron density between nuclei.

Destructive Interference (MO Theory)

The subtractive combination of atomic wavefunctions (e.g., \text{\textPsi}_{\text{\textsigma}^*} = \text{\textpsi}_{1s\text{A}} - \text{\textpsi}_{1s\text{B}}) that yields an antibonding molecular orbital containing a nodal plane between nuclei.

Aufbau Process

The rule in Molecular Orbital Theory stating that electrons fill the lowest energy molecular orbital first.

Pauli Exclusion Principle

The principle stating that a maximum of $2\text{ }e^-$ can occupy any single orbital.

Hund's Rule

The rule stating that degenerate orbitals having equal energies are filled singly before electrons pair up.

Bond Order

A quantitative measure calculated as \text{Bond Order} = \frac{(\text{\textnum} e^-\text{ in bonding MOs}) - (\text{\textnum} e^-\text{ in antibonding MOs})}{2}, where stable species display a positive value.

End-on Overlap

Orbital overlap occurring along the internuclear axis between $2p$ orbitals that is larger in magnitude and produces sigma (\text{\textsigma}) orbitals.

Side-on Overlap

Orbital overlap occurring perpendicular to the internuclear axis between $2p$ orbitals that is smaller in magnitude and produces pi (\text{\textpi}) orbitals.

Valence-Bond (VB) Theory

A theory that qualitatively describes how atomic orbitals of dissociated atoms overlap to form individual covalent bonds, with each atom maintaining its own atomic orbitals.

Orbital Hybridization

A mathematical procedure in which standard atomic orbitals of an atom are mixed to form new hybrid atomic orbitals used to explain molecular shapes.

sp Hybridization

The mixing of one $s$ and one $p$ orbital to produce two $sp$ hybrid orbitals in a linear geometric arrangement, leaving two $p$ orbitals unhybridized.

sp^2 Hybridization

The mixing of one $s$ and two $p$ orbitals to produce three $sp^2$ hybrid orbitals in a trigonal planar arrangement, leaving one $p$ orbital unhybridized.

sp^3 Hybridization

The mixing of one $s$ and three $p$ orbitals to form four $sp^3$ hybrid orbitals arranged tetrahedrally, each having a small lobe and a large bonding lobe.

sp^3d Hybridization

The mixing of one $s$, three $p$, and one $d$ orbital to form five $sp^3d$ hybrid orbitals describing five electron groups in a trigonal-bipyramidal arrangement.

sp^3d^2 Hybridization

The mixing of one $s$, three $p$, and two $d$ orbitals to form six $sp^3d^2$ hybrid orbitals describing six electron groups in an octahedral arrangement.

Double Covalent Bond

A covalent bond consisting of one sigma (\text{\textsigma}) bond formed by end-on overlap of hybrid orbitals and one pi (\text{\textpi}) bond formed by side-on overlap of unhybridized $p$ orbitals.

Triple Covalent Bond

A covalent bond consisting of one sigma (\text{\textsigma}) bond formed by $sp$ hybrid orbitals and two pi (\text{\textpi}) bonds formed by two pairs of unhybridized $p$ orbitals.