CHEM V

Covalent Bond

a bond formed by the sharing of electrons between atoms.

Molecule

a neutral group of atoms joined together by covalent bonds.

Diatomic molecule

a molecule consisting of two atoms.

Molecular compound

a compound that is composed of molecules.

Molecular formula

a chemical formula of a molecular compound that shows the kinds/numbers of atoms present in a molecule of a compound.

Single covalent bond

a bond formed when two atoms share a pair of electrons

Structural formula

a chemical formula that shows the arrangement of atoms in a molecule or a polyatomic ion; each dash between a pair of atoms indicates a pair of shared e-.

Unshared pair

a pair of valence e- that is not shared between atoms.

Double covalent bond

a bond in which two atoms share two pairs of e-

Triple covalent bond

a covalent bond in which 3 pairs of e- are shared by two atoms

Coordinate covalent bond

a covalent bond in which one atom contributes both bonding e-.

Bond dissociation energy

the energy required to break the bond between 2 covalently bonded atoms; expressed in kJ per mol of substance.

Resonance structure

one of the two or more equally valid e- dot structures of a molecule or polyatomic ion.

Molecular orbital

\: an orbital that applies to the entire molecule.

Polyatomic ion:

a tightly bound group of atoms that behaves as a unit & has a positive or negative charge.

Bonding orbital

a molecular orbital that can be occupied by 2 e- of a covalent bond

Sigma bond

a bond formed when 2 atomic orbitals combine to form a molecular orbital that is symmetrical around the axis connecting the 2 atomic nuclei

Pi bond

a covalent bond in which the bonding e- are most likely to be found in sausage shaped regions above & below the bond axis of the bonded atoms.

Tetrahedral Angle

a bond angle of 109.5 that results when a central atom forms 4 bonds directed toward the center of a regular tetrahedron.

VSEPR theory

valence-shell electron-pair repulsion theory; because e- pairs repel, molecules adjust their shapes so that valence e- pairs are as far apart as possible.

Hybridization

the mixing of several atomic orbitals to form the same total number of equivalent hybrid orbitals.

nonpolar covalent bond

\: a covalent bond in which the e- are shared equally by the 2 atoms

Polar covalent bond

\: a covalent bond between atoms in which the e- are shared unequally.

Polar molecule

\: a molecule in which one side of the molecule is slightly negative & the opposite side is slightly positive

Dipole

\: a molecule that has two poles, or regions, with opposite charges

Van der Waals forces

the two weakest intermolecular attractions-dispersion interactions & dipole forces.

Dipole interaction

intermolecular forces resulting from the attraction of oppositely charged regions of polar molecules

Dispersion force

\: attraction between molecules caused by the e- motion on one molecule affecting the e- motion on the other through electrical forces; weakest interactions between molecules.

Hydrogen bond

attractive forces in which a H covalently bonded to a very electronegative atom is also weakly bonded to an unshared e- pair of another electronegative atom.

Network solid

a solid in which all of the atoms are covalently bonded to each other.