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Arbitrary numbers that can be used as mechanical aids in writing formulas and balancing equations, for single- atom ions they correspond to the charge on the ion, more electronegative atoms are assigned negative oxidation numbers (also called Oxidation states).

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Solubility Product Principle

The solubility product constant expression for a slightly soluble compound is the product of the concentrations of the constituent ions, each raised to the power that corresponds to the number of ions in one formula unit.

Metalloids

Elements with properties intermediate between metals and nonmetals: B, Al, Si, Ge, As, Sb, Te, Po, and At.

Semiconductor

A substance that does not conduct electricity at low temperatures but does so at higher temperatures.

Polymorphous

Refers to substances that crystallize in more than one crystalline arrangement.

Percentage Ionization

The percentage of the weak electrolyte that ionizes in a solution of given concentration.

Pairing Energy

Energy required to pair two electrons in the same orbital.

Nitrogenases

A class of enzymes found in bacteria within root nodules in some plants, which catalyze reactions by which N2 molecules from the air are converted to ammonia.

 

Metal

An element below and to the left of the stepwise division (metalloids) in the upper right corner of the periodic table, about 80% of the known elements are metals.

Lewis Dot Formula (Electron Dot Formula)

Representation of the core of a molecule, ion or formula unit by showing atomic symbols and only outer shell electrons.

Heat of Fusion

The amount of heat required to melt one gram of solid at its melting point with no change in temperature. Usually expressed in J/g. The molar heat of fusion is the amount of heat required to melt one mole of a solid at its melting point with no change in temperature and is usually expressed in kJ/mol.

Electrode Potentials

Potentials, E, of half-reactions as reductions versus the standard hydrogen electrode.

Radical

An atom or group of atoms that contains one or more unpaired electrons (usually very reactive species)

Halogens

Group VIIA elements: F, Cl, Br, I

Corrosion

Oxidation of metals in the presence of air and moisture.

Specific Heat

The amount of heat required to raise the temperature of one gram of substance one degree Celsius.

Ferromagnetism

The ability of a substance to become permanently magnetized by exposure to an external magnetic field.

Dispersing Medium

The solvent-like phase in a colloid.

Half-Life

The time required for half of a reactant to be converted into product(s). The time required for half of a given sample to undergo radioactive decay.

Lone Pair

Pair of electrons residing on one atom and not shared by other atoms, unshared pair.

Square Planar

A term used to describe molecules and polyatomic ions that have one atom in the center and four atoms at the corners of a square.