CHEMISTRY GLOSSARY

Schiff base    →   Schiffova baza

Schiff base is a class of compounds derived by the chemical reaction (condensation) of aldehydes or ketones with aromatic amines, for example

They were named after the German chemist Hugo Schiff (1834-1915).

ion exchanger    →   ionski izmjenjivač

Ion-exchanger is a solid or liquid material containing ions that are exchangeable with other ions with a like charge that are present in a solution in which the material is insoluble. Ion-exchange resins consist of various copolymers having a cross-linked three-dimensional structure to which ionic groups have been attached.

iridium    →   iridij

Iridium was discovered by Smithson Tennant (England) in 1803. The origin of the name comes from the Latin word iris, meaning rainbow, because its salts are highly colored. It is heavy, brittle, white metal. Unreactive in air, water and acids. Attacked by fused NaOH. Metal ignites and burns readily. Iridium is found in gravel deposits with platinum. Used with osmium to tip gold pen points, to make crucible and special containers. Also to make alloys used for standard weights and measures and heat-resistant alloys. Also as hardening agent for platinum.

ketal    →   ketal

Ketals are organic compounds formed by addition of an alcohol to a ketone. If one molecule of ketone (RR’CO) reacts with one molecule of alcohol (R"OH) then a hemiketal is formed. The rings of ketose sugars are hemiketals. Further reaction produces a full ketal (RR’C(OR")₂). This term, once abandoned, has been reinstated as a subclass of acetals.

ketone    →   keton

Ketones are compounds in which a carbonyl group is bonded to two carbon atoms: R₁R₂C=O (neither R may be H). They are derived by oxidation of secondary alcohols. The simplest member of the series is acetone, (CH₃)₂CO.

selenide    →   selenid

Selenides are compounds having the structure R-Se-R (R not equal to H). They are thus selenium analogues of ethers. Also used for metal salts of H₂Se.

silanes    →   silani

Silanes are saturated silicon hydrides, analogues of the alkanes (compounds of the general formula Si_nH_2n+2).

smog    →   smog

Smog is a mixture of smoke and fog. The term is used to describe city fogs in which there is a large proportion of particulate matter (tiny pieces of carbon from exhausts) and also a high concentration of sulphur and nitrogen gases.

structural isomer    →   strukturni izomer

Structural isomers are compounds that have the same formula, but different constituents. Dimethyl ether (CH₃OCH₃) and ethanol (CH₃CH₂OH), for example, are constitutional isomers with general formula C₃H₆O.

superconductivity    →   supravodljivost

Superconductivity is the phenomenon in which certain metals, alloys, and compounds below a certain temperature, the transition point (T_c), lose electrical resistance and magnetic permeability, i.e. have infinite electrical conductivity (Meissner effect and Josephson effect).