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 and 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 electrons
unshared pair
a pair of valence electrons that is not shared between atoms
double covalent bond
a bond in which two atoms share two pairs of electrons
triple covalent bond
a bond in which three pairs of electrons are shared by two atoms
coordinate covalent bond
a covalent bond in which one atom contributes both bonding electrons
polyatomic ion
a tightly bound group of atoms that behaves as a unit and has a positive or negative charge
bond dissociation energy
the energy required to break the bond between two covalently bonded atoms; this value is usually expressed in kJ per mol of substance
resonance structure
one of the two or more equally valid electron dot structures of a molecule or polyatomic ion
molecular orbital
an orbital that applies to the entire molecule
bonding orbital
a molecular orbital that can be occupied by two electrons of a covalent bond
sigma bond
a bond formed when two atomic orbitals combine to form a molecular orbital that is symmetrical around the axis connecting the two atomic nuclei
pi bond
a covalent bond in which the bonding electrons are most likely to be found in sausage-shape regions above and below the bond axis of the bonded atoms
tetrahedral angle
a bond angle of 109.5 degrees that results when a central atom forms four bonds directed toward the center of a rectangular tetrahedron
VSEPR theory
valence shell electron-pair repulsion theory; because electrons pairs repel, molecules adjust their shapes so that valence electron 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 electrons are shared equally by the two atoms
polar covalent bond
polar bond; a covalent bond between atoms in which the electrons are shared unequally
polar molecule
a molecule in which one side of the molecule is slightly negative and 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 and dipole forces
dipole interactions
intermolecular forces resulting from the attraction of oppositely charged regions of polar molecules
dispersion forces
attractions between molecules caused by the electron motion on one molecule affecting the electron motion on the other through electrical forces; these are the weakest interactions between molecules
hydrogen bonds
attractive forces in which a hydrogen covalently bonded to a very electronegative atom is also weakly bonded to an unshared electron pair of another electronegative atom
network solid
a solid in which all of the atoms are covalently bonded to each other