Glossary of chemical terms

Zeeman effect
	Zeeman effect is the splitting of the lines in a spectrum when the source of the spectrum is exposed to a magnetic field. It was discovered in 1896 by Pieter Zeeman (1865-1943).
zeolite
	Zeolite is a natural or synthetic hydrated aluminosilicate with an open three-dimensional crystal structure, in which water molecules are held in cavites in the latice. The water can be driven off by heating and the zeolite can then absorb other molecules of suitable size. Zeolites are used for separating mixtures by selective absorption.
zeotrope
	Zeotrope is a liquid mixture that shows no maximum or minimum when vapor pressure is plotted against composition at constant temperature. See Azeotrope.
zero-order reaction
	Zero-order reaction is a reaction for which the rate of reaction is independent of the concentration of reactants.
zeta potential
	Zeta potential (ζ) is the electric potential at the surface of a colloidal particle relative to the potential in the bulk medium at a long distance. Also called electrokinetic potential. Zeta potential (ζ) is the potential across the interface of all solids and liquids. Specifically, the potential across the diffuse layer of ions surrounding a charged colloidal particle, which is largely responsible for colloidal stability. Also called electrokinetic potential.
Ziegler process
	Ziegler process is an industrial process for the manufacture of high-density polyethene using catalysts of titanium(IV) chloride (TiCl4) and aluminium alkyls (e.g. triethylaluminium, Al(C2H5)3). The process was introduced in 1953 by the German chemist Karl Ziegler (1898-1973). It allowed the manufacture of polythene at lower temperatures (about 60 °C) and pressures (about 1 atm) than used in the original process.
zwitterion
	Zwitterion is an ion that has a positive and negative charge on the same group of atoms. Zwitterions can be formed from compounds that contain both acid groups and basic groups in their molecules. It is also called ampholyte ion.

 

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