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

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Common Ion Effect

Suppression of ionization of a weak electrolyte by the presence in the same solution of a strong electrolyte containing one of the same ions as the weak electrolyte.

Associated Ions

Short-lived species formed by the collision of dissolved ions of opposite charges.

Sigma Orbital

Molecular orbital resulting from head-on overlap of two atomic orbitals.

Valence Shell Electron Pair Repulsion Theory

Assumes that electron pairs are arranged around the central element of a molecule or polyatomic ion so that there is maximum separation (and minimum repulsion) among regions of high electron density.

 

Crystal Lattice

A pattern of arrangement of particles in a crystal.

Fast Neutron

A neutron ejected at high kinetic energy in a nuclear reaction.

First Law of Thermodynamics

The total amount of energy in the universe is constant (also known as the Law of Conservation of Energy) energy is neither created nor destroyed in ordinary chemical reactions and physical changes.

Electrochemistry

Study of chemical changes produced by electrical current and the production of electricity by chemical reactions.

Base

A substance that produces OH (aq) ions in aqueous solution. Strong soluable bases are soluble in water and are completely dissociated. Weak bases ionize only slightly.

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.