CHEMISTRY GLOSSARY

non-polar solvent    →   nepolarno otapalo

Non-polar solvent is a liquid with non-polar molecules. It dissolves covalent compounds, non-water solvent.

dissociation    →   disocijacija

Dissociation is the process by which a chemical combination breaks up into simpler constituents as a result of either added energy (dissociated by heat), or the effect of a solvent on a dissolved polar compound (electrolytic dissociation). It may occur in the gaseous, solid, or liquid state, or in a solution.

An example of dissociation is the reversible reaction of hydrogen iodide at high temperatures

The term dissociation is also applied to ionisation reactions of acids and bases in water. For example

which is often regarded as a straightforward dissociation into ions

dissociation constant    →   konstanta disocijacije

Dissociation constant is a constant whose numerical value depends on the equilibrium between the undissociated and dissociated forms of a molecule. A higher value indicates greater dissociation.

The term dissociation is also applied to ionisation reactions of acids and bases in water. For example

which is often regarded as a straightforward dissociation into ions

The equilibrium constant of such a dissociation is called the acid dissociation constant or acidity constant, given by

The concentration of water [H₂O] can be taken as constant.

Similarly, for a base, the equilibrium

is also a dissociation; with the base dissociation constant or basicity constant, given by

K_a (K_b) is a measure of the strength of the acid (base).

nucleophile    →   nukleofil

Nucleophiles are negatively charged or bear a partial negative charge. Examples are lone pairs or a hydroxide ion.

oligomer    →   oligomer

Oligomer is a substance consisting of molecules of intermediate relative molecular mass (molecular weight), the structure of which essentially comprises the multiple repetitions of units derived, actually or conceptually, from molecules of low relative molecular mass. In contrast to a polymer, the properties of an oligomer can vary significantly with the removal of one or a few of its units.

oligosaccharide    →   oligosaharid

Oligosaccharides are carbohydrates containing from three to ten monosaccharide units, each joined to the next by a glycoside bond.

osmometry    →   osmometrija

Osmometry is a determination of the average molecular weight of a dissolved substance from measurements of osmotic pressure.

oxonium ion    →   oksonijev ion

Oxonuim ion (H₃O⁺) is formed when a molecule of water binds with a proton.

electron affinity    →   elektronski afinitet

Electron affinity (E_A) is the energy change occurring when an atom or molecule gains an electron to form a negative ion. For an atom or molecule X, it is the energy released for the electron-attachment reaction

This is often measured in electronvolts. Alternatively, the molar enthalpy change, ΔH, can be used.

enantiomer    →   enantiomer

Enantiomers are a chiral molecule and its non-superposable mirror image. The two forms rotate the plane of polarised light by equal amounts in the opposite directions. Also called optical isomers.