CHEMISTRY GLOSSARY

helium II    →   helij II

See Superfluid helium

hfcs    →   hfcs

HFCS is abbreviation for high fructose corn syrup.

hologram    →   hologram

Hologram is reconstruction of an object in three dimensions by using the properties of laser light (interference). A hologram takes a picture, but displays it so the side and the rear can be seen.

crystal system    →   kristalni sustav

Crystal system is a method of classifying crystalline substances on the basis of their unit cell. There are seven unique crystal systems. The simplest and most symmetric, the cubic (or isometric) system, has the symmetry of a cube. The other six systems, in order of decreasing symmetry, are hexagonal, tetragonal, rhombohedral (also known as trigonal), orthorhombic, monoclinic and triclinic.

Crystal system	Unit-cell	Conditions on unit-cell edges and angles
cubic		a=b=c α=β=γ=90°
hexagonal		a≠c α=γ=90° β=120°
tetragonal		a=b≠c α=β=γ=90°
rhombohedral		a=b=c α=β=γ≠90°
orthorhombic		a≠b≠c α=β=γ=90°
monoclinic		a≠b≠c α=γ=90°≠β
triclinic		a≠b≠c α≠β≠γ≠90°

invertase    →   invertaza

Invertase (sucrase, saccharase, beta-fructofuranosidase) is an enzyme present in yeast and in the intestinal juice of animals that catalyze the hydrolysis of table sugar (sucrose, saccharose) to the simple sugars, glucose and fructose. This equimolar mixture of glucose and fructose is called invert sugar.

ISE    →   ISE

ISE is abbreviation for ion selective electrode.

deionised water    →   deionizirana voda

Deionised water is water from which ionic salts have been removed by ion-exchange. It is used for many purposes as an alternative to distilled water.

dielectric constant    →   dielektrična konstanta

Dielectric constant or permittivity (ε) is an index of the ability of a substance to attenuate the transmission of an electrostatic force from one charged body to another. The lower the value, the greater the attenuation. The standard measurement apparatus utilises a vacuum whose dielectric constant is 1. In reference to this, various materials interposed between the charged terminal have the following value at 20 °C:

The exceptionally high value for water accounts for its unique behaviour as a solvent and in electrolytic solutions. Dielectric constant values decrease as the temperature rises.

differential thermal analysis    →   diferencijalna termalna analiza

Differential thermal analysis (DTA) is a technique that is often used to analyze materials that react or decompose at higher temperatures. The difference in temperature between the sample and an inert reference material is monitored as both are heated in a furnace. Phase transitions and chemical reactions taking place in the sample on heating cause the temperature difference to become larger, at temperatures that are characteristic of the sample.

Earth’s crust    →   Zemljina kora

Crust is outer layer of the solid earth, above the Mohorovicic discontinuity. Its thickness averages about 35 km on the continents and about 7 km below the ocean floor, and has the approximate chemical composition: