Chemical Bonding and Molecular Geometry

Vocabulary

bond length

distance between the nuclei of the atoms forming a bond, usually expressed in picometers (pm) or angstroms (Å)

bonding electron

electron that is part of a covalent bond

covalent bond

chemical bond that forms when valence electrons are shared between atoms

dipole

molecule with partial positive and partial negative charges

dipole-dipole interaction

attractive or repulsive force between two polar molecules resulting from partial positive and partial negative charges of the molecules

double bond

covalent bond in which two pairs of electrons are shared between two atoms

electronegativity

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

formal charge

hypothetical charge assigned to an atom in a molecule with the assumption that bonding electrons are shared equally

free radical

atom, molecule, or ion with one or more unpaired electrons

hydrogen bond

weak intermolecular bond between a hydrogen atom of one molecule and a highly electronegative atom of a nearby molecule. The electronegative atom is usually fluorine, oxygen, or nitrogen.

hypervalent

having more than an octet of valence electrons

induced dipole

polarized bond induced by an electric field

instantaneous dipole

dipole that forms because of a short-lived imbalance in charge distribution in an otherwise nonpolar atom or molecule

intermolecular force

attractive or repulsive force between a molecule and a nearby molecule, atom, or ion

intramolecular force

attractive or repulsive force between atoms that make up a molecule or between ions

ion-dipole interaction

electrostatic interaction between ions and polar ends of molecules with permanent dipoles

ionic bond

electrostatic force that holds cations and anions together

Lewis structure

model that represents covalent bonds and nonbonding electrons with symbols, dots, and lines

London dispersion force

interaction between induced, instantaneous dipoles in nonpolar molecules or atoms

lone pair

valence electron pair that does not form a bond

molecular structure

three-dimensional shape of a molecule that takes into account bonding and nonbonding electron pairs and molecular rotations to minimize their interactions

nonpolar covalent bond

covalent bond in which the nuclei of the bonded atoms exert equal or nearly equal force on the shared electrons

octet rule

rule that states that atoms tend to share or donate electrons such that the valence shell contains eight electrons (octet=ns+np=8)(\text{octet}=ns+np=8)

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.

polarizability

ability for dipole moments to change because of the presence of an applied electric field

resonance structure

one of two or more Lewis structures with multiple equivalent representations

single bond

covalent bond in which one pair of electrons is shared between two atoms

triple bond

covalent bond in which three pairs of electrons are shared between two atoms

valence electron

electron in the outermost shell of an atom

van der Waals force

dipole-dipole interaction, London dispersion force, or intermolecular force between permanent molecular dipoles