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

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Spectrum

Display of component wavelengths (colours) of electromagnetic radiation.

Kinetic Energy

Energy that matter processes by virtue of its motion.

Crystal Lattice Energy

Amount of energy that holds a crystal together, the energy change when a mole of solid is formed from its constituent molecules or ions (for ionic compounds) in their gaseous state.

yttrium

A rare trivalent metallic element, found in gadolinite and other minerals. Symbol: Y, at. wt.: 88.905, at. no.: 39, sp. gr.: 4.47. Cf."rare-earth element."

Yttrium has a silver-metallic luster and is relatively stable in air unless finely divided. Turnings of the metal, however, ignite in air if their temperature exceeds 400oC. Yttrium oxide is one of the most important compounds of yttrium and accounts for the largest use. It is widely used in making YVO4 europium, and Y2O3 europium phosphors to give the red color in color television tubes.

Electron Deficient Compounds

Compounds that contain at least one atom (other than H) that shares fewer than eight electrons.

Artificial Transmutation

An artificially induced nuclear reaction caused by the bombardment of a nucleus with subatomic particiles or small nucei.

Crystalline Solid

A solid characterized by a regular, ordered arrangement of particles.

Free Energy Change

The indicator of spontaneity of a process at constnt T and P. If delta-G is negative, the process is spontaneous.

Lewis Acid

Any species that can accept a share in an electron pair.

Lead Storage Battery

Secondary voltaic cell used in most automobiles.