CHEMISTRY GLOSSARY

francium    →   francij

Francium was discovered by Marguerite Perey (France) in 1939. Named for France, the nation of its discovery. It is highly rare and unstable, radioactive metal. Chemical properties similar to cesium. Francium is formed by decay of actinium. Produced by bombarding radium or astatine with neutrons. Since its isotopes have such short half-lives there are no commercially significant compounds of francium.

glacial acetic acid    →   ledena octena kiselina

Glacial acetic acid (CH₃COOH) is the pure compound, as distinguished from the usual water solutions known as acetic acid. It is a colorless liquid or crystalline substance (melting point 16.6 °C) with a pungent, vinegar odor.

glass    →   staklo

Glass is a brittle transparent solid with the molecular structure of a liquid. It is made by fusing together sand (SiO₂), soda (Na₂CO₃), and lime (CaCO₃) with small quantities other compounds. It is used for window panes and mirrors, for articles of table and culinary use, for lenses, and various articles of ornament.

complexometry    →   kompleksometrija

Complexometry is a volumetric analytic method which is based on titration of metal ion solutions with a substance that, combined with metal ions yields complex compounds, e.g. EDTA. The stoichiometric ratio of EDTA-metal in complexometric analyses is always 1:1, whatever the valency of the metal

corrosion    →   korozija

Corrosion is a harmful and undesirable construction material consumption by the chemical activity of its surroundings. Corrosion concept refers to metal and nonmetal construction materials, but it is usually used for metals, Corrosion of metal, according to the mechanism process, is divided into chemical (corrosion in nonelectrolytes) and electrochemical (corrosion in electrolytes).

Chemical corrosion appears by direct action of molecule of some element or compound on metal, thus directly creating corrosion products.

Electrochemical corrosion of metals occurs in electrolytes, so reduction of metal atom into free cation appears which by secondary processes gives molecules of compound which are considered a corrosion product.

cross-linking    →   umrežavanje

Cross-linking is an attachment of two chains of polymer molecules by bridges, composed of either an element, a group, or a compound, that join certain carbon atoms of the chains by primary chemical bonds, as indicated in the schematic diagram

Cross-linking occurs in nature in substances made up of polypeptide chains that are joined by the disulfide bonds of the cysteine residue, as in keratins or insulin. Cross-linking can be artificially effected, either adding a chemical substance (cross-linking agent), or by subjecting the polymer to high-energy radiation. Examples are: vulcanisation of rubber with sulphur, cross-linking of polystyrene with divinylbenzene, or cross-linking of polyethylene by means of high-energy radiation.

Cross-linking has the effect of changing a plastic from thermoplastic to thermosetting. Thus, it also increases strength, heat and electrical resistance, and especially resistance to solvents and other chemicals.

glycols    →   glikoli

Glycols are compounds that have two hydroxyl groups present in each molecule. The simplest member is ethylene glycol.

heat of formation    →   toplina nastajanja

Heat of formation or enthalpy of is formation the heat evolved or absorbed when one mole of a compound is formed in its standard state from its constituent elements.

herbicide    →   herbicid

Herbicide is any chemical compound used to kill pests that destroy agricultural production. Pesticide include herbicides (such as 2.4 D and Paraquat), which kill unwanted plants or weeds.

heroin    →   heroin

Heroin (diacetylmorphine) is a narcotic compound that is a synthetic derivative of morphine. The compound is easily absorbed by the brain, due to its lipid-like nature, and is used as a sedative and a powerful analgesic. Highly addictive, it is abused by drug users.