CHEMISTRY GLOSSARY

omega-3 fatty acids    →   omega-3 masne kiseline

Omega-3 fatty acids are polyunsaturated fatty acids, meaning they contain more than one double bond. The name omega-3 indicates that the first double bond occurs on the third carbon atom (n-3) from the methyl (-CH₃) end of the molecule (omega position). The three main omega-3 fatty acids are alpha-linolenic acid (ALA, 18:3n-3), eicosapentaenoic acid (EPA, 20:5n-3), and docosahexaenoic acid (DHA, 22:6n-3). ALA comes from plants. EPA and DHA come from fish.

Similarly, the first double bond in omega-6 fatty acids is located between the sixth and seventh carbon atom (n-6) from the methyl end of the fatty acid (omega end).

optical activity    →   optička aktivnost

Optical activity is the ability of a chiral molecule to rotate the plane of plane-polairzed light. Molecules of an optically active substance cannot be superimposed on their own mirror images, just as your left hand cannot be superimposed on your right when both are held palm-down.

optically active matter    →   optički aktivna tvar

Optically active matter, by polarized light passing through it, turns the flat of polarized light leftwards or rightwards.

ortho position    →   ortho položaj

Ortho position in organic chemistry is the one in which there are two same functional groups, tied to a ring of benzene in the positions 1 and 2. The abbreviation o- is used, for example, o-Hydroquinone is 1,2-dihydroxybenzene.

orthorhombic crystal system    →   ortorompski kristalni sustav

Orthorhombic crystal system is also known as the rhombic system. Minerals of the orthorhombic crystal system are referred to three mutually perpendicular axes, each of which is of a different length than the others.

Ostwald’s viscometer    →   Ostwaldov viskozimetar

Ostwald viscometer, also known as U-tube viscometer or capillary viscometer is a device used to measure the viscosity of the liquid with a known density. The method of determining viscosity with this instrument consists of measuring the time for a known volume of the liquid (the volume contained between the marks A and B) to flow through the capillary under the influence of gravity. Ostwald viscometers named after the German chemist Wilhelm Ostwald (1853-1932).

The instrument must first be calibrated with materials of known viscosity such as pure (deionized) water. Knowing the value of viscosity of one liquid, one can calculate the viscosity of other liquid.

where η₁ and η₂ are viscosity coefficients of the liquid and water, and ρ₁ and ρ₂ are the densities of liquid and water, respectively.

oxo compound    →   okso-spoj

Oxo compounds are organic compounds that contain the karbonyl group, C=O. The term thus embraces aldehydes, carboxylic acids, ketones, amides, and esters.

ozone    →   ozon

Ozone is an alotropic form of oxygen. It is an unstable blue gas with a pungent odour. It is a powerful oxidising agent. The gas is made by passing oxygen through a silent electric discharge.

paper chromatography    →   papirna kromatografija

Paper chromatography is one of the types of chromatography procedures which runs on a piece of specialized paper. It is a planar chromatography systems wherein a cellulose filter paper acts as a stationary phase on which separation of compounds occurs. The edge of the paper is immersed in a solvent, and the solvent moves up the paper by capillary action.

para position    →   para položaj

Para position in organic chemistry is the one in which there are two same functional groups tied to a ring of benzene in the position 1 and 4. The abbreviation p- is used, for example, p-Hydroquinone is 1,4-dihydroxybenzene.