Theories of Covalent Bonding

Vocabulary

antibonding molecular orbital

molecular orbital that induces a low electron density between two or more atoms. It is at a higher energy state than the atomic orbitals it is formed from.

bond angle

angle formed between two terminal groups and a central atom

bond dissociation energy

energy required to break a covalent bond

bond order

difference between the number of bonding and antibonding electrons, divided by two

bonding molecular orbital

molecular orbital that has a high electron density between two or more atoms due to the overlap of multiple atomic orbitals

dipole moment

vector quantity that defines the extent of the charge on either side of a polar covalent bond, with the direction that points from the positive side of the bond toward the negative side

electron-pair geometry

shape description for all electron pairs (bonding and nonbonding) about a central atom

electronegativity

tendency of an atom to attract electrons toward itself when forming bonds

homonuclear diatomic molecule

molecule consisting of two atoms of the same element, bound together by one or more covalent bonds

hybrid orbital

according to valence bond theory, an electron orbital that forms when two atomic orbitals combine to form a covalent bond

molecular geometry

shape formed by the central atom, considering only bonds to other elements

molecular orbital

mathematical function that gives the probability of locating an electron in a localized volume of space

molecular orbital theory

theory that atomic electron orbitals in covalent bonds are replaced by electron orbitals that belong to the entire molecule

nonpolar molecule

molecule with a dipole moment equal to zero

orbital

region in which an electron has a high probability of being located. Orbitals are described by the quantum numbers s, p, d, and f, which differ from each other by their shapes.

pi bond

bond formed when two orbitals overlap side by side on the same plane

polar covalent bond

covalent bond in which the electron density is more localized on one end of the bond. One end is slightly positive, and one end is slightly negative.

polar molecule

molecule with a specific dipole moment not equal to zero

sigma bond

bond formed when two orbitals overlap end to end

sp hybrid orbital

hybrid orbital that forms when one s and one p orbital combine

sp2 hybrid orbital

hybrid orbital that forms when one s and two p orbitals combine

sp3 hybrid orbital

hybrid orbital that forms when one s and three p orbitals combine

sp3d hybrid orbital

hybrid orbital that forms when one s, three p, and one d orbital combine

sp3d2 hybrid orbital

hybrid orbital that forms when one s, three p, and two d orbitals combine

valence bond theory

theory that the electrons in a covalent bond remain centralized around their original nuclei, and their atomic orbitals overlap

valence shell electron-pair repulsion (VSEPR) theory

covalent bond theory that uses the repulsive forces between single electrons and pairs of electrons about the central atom to predict their relative positions around the atomic nuclei