# 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

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 $(\text{octet}=ns+np=8)$

### 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