What is antibonding in molecular orbital theory?

In chemical bonding theory, an antibonding orbital is a type of molecular orbital (MO) that weakens the chemical bond between two atoms and helps to raise the energy of the molecule relative to the separated atoms.

What are the orbital types in MO theory?

Molecular orbital (MO) theory uses a linear combination of atomic orbitals (LCAO) to represent molecular orbitals resulting from bonds between atoms. These are often divided into three types, bonding, antibonding, and non-bonding. The molecular orbitals of a molecule can be illustrated in molecular orbital diagrams.

How are orbitals formed in MO theory?

Molecular orbitals are obtained by combining the atomic orbitals on the atoms in the molecule. Consider the H2 molecule, for example. One of the molecular orbitals in this molecule is constructed by adding the mathematical functions for the two 1s atomic orbitals that come together to form this molecule.

How are bonding and antibonding orbitals related in molecular orbital theory?

For a π-bond, corresponding bonding and antibonding orbitals would not have such symmetry around the bond axis, and are designated π and π* respectively. The next step in constructing an MO diagram is filling the newly formed molecular orbitals with electrons. Three general rules apply:

How are molecular orbitals formed in MO theory?

In MO theory, molecular orbitals form by the overlap of atomic orbitals. Atomic orbital energy correlates with electronegativity, as electronegative atoms hold electrons more tightly, lowering their energies. MO modeling is only valid when the atomic orbitals have comparable energy; when the energies differ greatly, the bonding mode becomes ionic.

What is the probability density of electrons in antibonding MO?

Thus the probability density of electrons in antibonding MO is less than that in either of atomic orbitals (ψA2 or ψB2). In a similar way, the combination of two 2s orbitals produces a bonding σ (2s) and antibonding σ* (2s) molecular orbitals.

What kind of nodal planes do antibonding orbitals have?

In homonuclear diatomic molecules, σ* ( sigma star) antibonding orbitals have no nodal planes passing through the two nuclei, like sigma bonds, and π* ( pi star) orbitals have one nodal plane passing through the two nuclei, like pi bonds.