Glossary: Z

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Zeeman effect.

The splitting of spectral lines when an external magnetic field is applied.

zeta potential. electrokinetic potential.

Electric potential across all phase boundaries between solids and liquids. In colloids, the zeta potential is the potential across the ion layer around a charged colloidal particle. Neutralizing the zeta potential can cause the colloid to precipitate.

zeolite.

Addition compounds of the type Na₂O·Al₂O₃·n SiO₂·m H₂O, with calcium sometimes replacing or present with the sodium. The sodium in the zeolite exchanges with calcium in water, making zeolites useful for water softening. The porous structure of zeolites also makes them effective molecular sieves used as gas adsorbents and drying agents. Artificial zeolites are used as ion exchange resins.

zero order reaction. Compare with first order reaction and second order reaction.

A reaction with a reaction rate that does not change when reactant concentrations change.

zero point energy.

A minimum possible energy for an atom or molecule predicted by quantum mechanics. Electrons stay in motion and bonds continue to vibrate even at absolute zero because of zero point energy.

zinc. Zn.

Element 30, atomic weight 65.37, a reactive gray metal that dissolves in acids, used to galvanize metals and in many alloys (e. g. brass and bronze).

zincography.

Process of etching unprotected parts of a zinc plate with strong acids to produce a printing surface.

zirconium. Zr.

Element 40, atomic weight 91.22, a hard, grayish, highly flammable crystalline metal that dissolves in hot concentrated acids. Used in steel manufacture and in nuclear reactor chambers because of its transparency to neutrons. Its silicate is used to make zircon used as a gemstone.

zone refining.

A method for purifying solids based on the fact that solutes tend to concentrate in the liquid when a solution is frozen. A solid bar is drawn slowly over a heat source and melted in a narrow band; impurities are carried along in the melted band until the end of the bar is reached.

zwitterion.

A particle that contains both positively charged and negatively charged groups. For example, amino acids (NH₂-CHR-COOH) can form zwitterions (⁺NH₃-CHR-COO^-)

zymase.

Enzymes present in yeast that catalyze fermentation of sugar into alcohol and carbon dioxide.

zymogen. proenzyme.

A protein that may be converted into an enzyme.

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Copyright © 1997-2010 by Fred Senese
Comments & questions to fsenese@frostburg.edu
Last Revised 02/23/18.URL: http://antoine.frostburg.edu/chem/senese/101/glossary/z.shtml