Hybrid orbitals, sigma and pi bonds, and molecular orbitals. Master the vocabulary of modern bonding theories.
These terms were extracted from Chemistry by OpenStax, eCampusOntario (© 2016 Rice University; adapted by BCcampus) which is licensed under a Creative Commons Attribution 4.0 International License.
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coexistence of orbitals from two different atoms sharing the same region of space, leading to the formation of a covalent bond
Valence bond theory describes a covalent bond as the overlap of half-filled atomic orbitals (each containing a single electron) that yield a pair of electrons shared between the two bonded atoms.
plane separating different lobes of orbitals, where the probability of finding an electron is zero
Along the axis itself, there is a node, that is, a plane with no probability of finding an electron.
covalent bond formed by side-by-side overlap of atomic orbitals; the electron density is found on opposite sides of the internuclear axis
A pi bond (π bond) is a type of covalent bond that results from the side-by-side overlap of two p orbitals, as illustrated in Figure 4.
covalent bond formed by overlap of atomic orbitals along the internuclear axis
Single bonds in Lewis structures are described as σ bonds in valence bond theory.
description of bonding that involves atomic orbitals overlapping to form σ or π bonds, within which pairs of electrons are shared
We need to understand the additional concepts of valence bond theory, orbital hybridization, and molecular orbital theory to understand these observations.
orbital created by combining atomic orbitals on a central atom
The new orbitals that result are called hybrid orbitals.
model that describes the changes in the atomic orbitals of an atom when it forms a covalent compound
We need to understand the additional concepts of valence bond theory, orbital hybridization, and molecular orbital theory to understand these observations.
one of a set of two orbitals with a linear arrangement that results from combining one s and one p orbital
This hybridization process involves mixing of the valence s orbital with one of the valence p orbitals to yield two equivalent sp hybrid orbitals that are oriented in a linear geometry (Figure 3).
one of a set of three orbitals with a trigonal planar arrangement that results from combining one s and two p orbitals
The valence orbitals of a central atom surrounded by three regions of electron density consist of a set of three sp² hybrid orbitals and one unhybridized p orbital.
one of a set of four orbitals with a tetrahedral arrangement that results from combining one s and three p orbitals
The valence orbitals of an atom surrounded by a tetrahedral arrangement of bonding pairs and lone pairs consist of a set of four sp³ hybrid orbitals.
one of a set of five orbitals with a trigonal bipyramidal arrangement that results from combining one s, three p, and one d orbital
We use the 3s orbital, the three 3p orbitals, and one of the 3d orbitals to form the set of five sp³d hybrid orbitals (Figure 14) that are involved in the P–Cl bonds.
one of a set of six orbitals with an octahedral arrangement that results from combining one s, three p, and two d orbitals
To bond six fluorine atoms, the 3s orbital, the three 3p orbitals, and two of the 3d orbitals form six equivalent sp³d² hybrid orbitals, each directed toward a different corner of an octahedron.
molecular orbital located outside of the region between two nuclei; electrons in an antibonding orbital destabilize the molecule
The asterisk signifies that the orbital is an antibonding orbital.
number of pairs of electrons between two atoms; it can be found by the number of bonds in a Lewis structure or by the difference between the number of bonding and antibonding electrons divided by two
The net contribution of the electrons to the bond strength of a molecule is identified by determining the bond order that results from the filling of the molecular orbitals by electrons.
molecular orbital located between two nuclei; electrons in a bonding orbital stabilize a molecule
The structure and overall outline of the bonding orbitals of ethane are shown in Figure 12.
orbitals that have the same energy
Except for their orientation, the πpy and πpz orbitals are identical and have the same energy; they are degenerate orbitals.
phenomenon in which a material is not magnetic itself but is repelled by a magnetic field; it occurs when there are only paired electrons present
Materials in which all of the electrons are paired are diamagnetic and weakly repel a magnetic field.
molecule consisting of two identical atoms
Such molecules are called homonuclear diatomic molecules.
technique for combining atomic orbitals to create molecular orbitals
The mathematical process of combining atomic orbitals to generate molecular orbitals is called the linear combination of atomic orbitals (LCAO).
region of space in which an electron has a high probability of being found in a molecule
We need to understand the additional concepts of valence bond theory, orbital hybridization, and molecular orbital theory to understand these observations.
visual representation of the relative energy levels of molecular orbitals
The relative energy levels of atomic and molecular orbitals are typically shown in a molecular orbital diagram (Figure 8).
model that describes the behavior of electrons delocalized throughout a molecule in terms of the combination of atomic wave functions
We need to understand the additional concepts of valence bond theory, orbital hybridization, and molecular orbital theory to understand these observations.
phenomenon in which a material is not magnetic itself but is attracted to a magnetic field; it occurs when there are unpaired electrons present
Such attraction to a magnetic field is called paramagnetism, and it arises in molecules that have unpaired electrons.
molecular orbital formed by side-by-side overlap of atomic orbitals, in which the electron density is found on opposite sides of the internuclear axis
Rotation about the internuclear axis is much more difficult for multiple bonds; however, this would drastically alter the off-axis overlap of the π bonding orbitals, essentially breaking the π bond.
antibonding molecular orbital formed by out of phase side-by-side overlap of atomic orbitals, in which the electron density is found on both sides of the internuclear axis, and there is a node between the nuclei
The side-by-side overlap of two p orbitals gives rise to a pi (π) bonding molecular orbital and a π* antibonding molecular orbital.
molecular orbital in which the electron density is found along the axis of the bond
In other words, rotation around the internuclear axis does not change the extent to which the σ bonding orbitals overlap because the bonding electron density is symmetric about the axis.
antibonding molecular orbital formed by out-of-phase overlap of atomic orbital along the axis of the bond, generating a node between the nuclei
Sigma (σ) and sigma-star (σ*) molecular orbitals are formed by the combination of two s atomic orbitals.
change that causes σp orbitals to be less stable than πp orbitals due to the mixing of s and p-based molecular orbitals of similar energies.
This switch in orbital ordering occurs because of a phenomenon called s-p mixing. s-p mixing does not create new orbitals; it merely influences the energies of the existing molecular orbitals.