Chem 111 Exam 3

percent composition by mass

The percent of the total mass contributed by each element in a compound.

empirical formula mass

The mass in amu of one empirical formula of a compound.

bond length

Distance between two nuclei connected by a covalent bond

coordinate colavent bond

A covalent bond in which one of the atoms donates both electrons

dative body

A covalent bond in which one of the atoms donates both electrons

dipole moment (μ)

A quantitative measure of the polarity of a bond

double bond

A multiple bond in which the atoms share two pairs of electrons

electronegativity

The ability of an atom in a compound to draw electrons to itself

formal change

Method of electron “bookkeeping” in which shared electrons are divided equally between the atoms that share them

free radical

A molecule with an odd number of electrons

lewis acid

A species that can accept a pair of electrons

Lewis Base

A species that can donate a pair of electrons

lewis structure

A representation of covalent bonding in which shared electron pairs are shown either as dashes or as pairs of dots between two atoms, and lone pairs are shown as pairs of dots on individual atoms.

lone pair

A pair of valence electrons that are not involved in covalent bond formation

multiple bond

A chemical bond in which two atoms share two or more pairs of electrons

nonpolar

Having a uniform distribution of electron density

octet rule

Rule stating that atoms will lose, gain, or share electrons to achieve a noble gas electron configuration.

percent ionic character

The ratio of the observed dipole moment (µ) to the calculated dipole moment (µ), multiplied by 100

polar

Having a nonuniform electron density

polar covalent bond

Bonds in which electrons are unequally shared

resonance structures

Two or more equally valid Lewis structures for a single molecule that differ only in the positions of electrons

single bond

A pair of electrons shared by two atoms

triple bond

A multiple bond in which the atoms share three pairs of electrons

axial

Describes the two bonds that form an axis perpendicular to the trigonal plane in trigonal bipyramidal geometry

bond angle

The angle between two adjacent A−B bonds

dipole-dipole interactions

Attractive forces that act between polar molecules

electron domain

A lone pair or a bond, regardless of whether the bond is single, double, or triple.

electron domain geometry

The arrangement of electron domains (bonds and lone pairs) around a central atom

equatorial

Describes the three bonds that are arranged in a trigonal plane in a trigonal bipyramidal geometry

hybridization

The mixing of atomic orbitals

hybrid orbitals

Orbitals formed by hybridization of some combination of s, p, or d atomic orbitals

hydrogen bonding

A special type of dipole-dipole interaction that occurs only in molecules that contain H bonded to a small, highly electronegative atom, such as N, O, or F

instantaneous dipole

A fleeting nonuniform distribution of electron density in a molecule without a permanent dipole

intermolecular forces

The attractive forces that hold particles together in the condensed phase

ion-dipole interactions

Coulombic attractions between ions and polar molecules

dispersion forces

Attractive forces that act between all molecules, including nonpolar molecules, resulting from the formation of instantaneous dipoles and induced dipoles.

molecular geometry

The arrangement of bonded atoms

molecular orbitals

Orbitals that result from the interaction of atomic orbitals of bonding atoms

polarized

Describes a molecule in which a dipole moment has been induced

structural isomer

Molecules that have the same chemical formula but different arrangements of atoms

valence bond theory

Atoms share electrons when an atomic orbital on one atom overlaps with an atomic orbital on the other

valence-shell electron-pair repulsion (VSEPR)

A model that accounts for electron pairs in the valence shell of an atom repelling one another.

van der Waals forces

The attractive forces that hold particles together in the condensed phases that include dipole-dipole interactions (including hydrogen bonding) and dispersion forces.

solvation

Process by which solute particles become surrounded by solvent molecules

entropy

A thermodynamic state function that describes how dispersed a system’s energy is

miscible

Mutually soluble in any proportions