Chapter 7 Ionic and Metallic Bonding
Alloy
A mixture composed of two or more elements, at
least one of which is a metal.
Chemical Formula
An expression that indicates the number and type
of atoms present in the smallest representative
unit of a substance.
Coordination number
The number of ions of opposite charge that
surround each ion in a crystal.
Electron Dot Structure
A notation that depicts valence electrons as dots
around the atomic symbol of the element; the
symbol represents the inner electrons and atomic
nucleus; also called Lewis Dot Structure.
Formula Unit
The lowest whole-number ratio of ions in an ionic
compound; in magnesium chloride, the ratio of
magnesium ions to chloride ions is 1:2 and the
formula unit is MgCl2.
Halide Ion
A negative ion formed when a halogen atom
gains an electron.
Ionic Bond
The electrostatic attraction that binds oppositely
charged ions together.
Ionic Compound
A compound composed of positive and negative
ions.
Metallic Bond
The force of attraction that holds metals together;
it consists of the attraction of free-floating
valence electrons for positively charged metal
ions.
Octet Rule
Atoms react by gaining or losing electrons so as
to acquire the stable electron structure of a noble
gas, usually eight valence electrons.
Valence Electron
An electron in the highest occupied energy level
of an atom.
Ch. 8 Covalent Bonding
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.
Bonding Orbital
A molecular orbital that can be occupied by two
electrons of a covalent bond.
Covalent Bond
A bond formed by the sharing of electrons
between atoms.
Coordinate covalent bond
A covalent bond in which one atom contributes
both bonding electrons.
Diatomic molecule
A molecule consisting of two atoms.
Dipole
A molecule that has two poles, or regions with
opposite charges.
Dipole Interactions
Intermolecular forces resulting from the attraction
of oppositely charged regions of polar molecules.
Dispersion forces
Double covalent bond
Attractions between molecules caused by the
electron motion on one molecule affecting the
electron motion on the other through electrical
forces: these are weakest interactions between
molecules.
A bond in which two atoms share two pairs of
electrons.
Hybridization
Hydrogen bonds
The mixing of several atomic orbitals to form the
same total number of equivalent hybrid orbitals.
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.
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.
Molecular orbital
An orbital that applies to the entire molecule.
Molecule
A neutral group of atoms joined together by
covalent bonds.
Network solid
A solid in which all of the atoms are covalently
bonded to each other.
Nonpolar covalent bond
A covalent bond in which the electrons are shared
equally by the two atoms.
Pi bond
Polar bond
A covalent bond in which the bonding electrons
are most likely to be found in sausage-shaped
regions above and below the bond axis of the
bonded atoms.
A covalent bond between atoms in which the
electrons are shared unequally. Also known as a
polar covalent bond.
Polar covalent bond
A covalent bond between atoms in which the
electrons are shared unequally. Also known as a
polar bond.
Polar molecule
A molecule in which one side of the molecule is
slightly negative and the opposite side is slightly
positive.
Polyatomic ion
A tightly bound group of atoms that behaves as a
unit and has a positive or negative charge.
Resonance structure
One of the two or more equally valid electron dot
structures of a molecule or polyatomic ion.
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.
Single covalent bond
Structural formula
Tetrahedral angle
A bond formed when two atoms share a pair of
electrons.
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.
A bond angle of 109.5° that results when a central
atom forms four bonds directed toward the center
of a regular tetrahedron.
Triple covalent bond
A covalent bond in which three pairs of electrons
are shared by two atoms.
Unshared pair
A pair of valence electrons that is not shared
between atoms.
van der Waals forces
VSEPR theory
The two weakest intermolecular attractionsdispersion interactions and dipole forces
Valence-shell electron-pain repulsion theory;
because electron pairs repel, molecules adjust
their shapes so that valence electron pairs are as
far apart as possible.