CHEMISTRY GLOSSARY

dienes    →   dieni

Dienes are unsaturated organic compounds that contain two fixed double bonds between carbon atoms. Dienes in which the two double-bond units are linked by one single bond are termed conjugated.

electron pair    →   elektronski par

Electron pair is two electrons within one orbital with opposite spins responsible for a chemical bond.

hydrophilic    →   hidrofilan

Hydrophilic is having a strong tendency to bind or absorb water, which results in swelling and formation of reversible gels. This property is characteristic of carbohydrates.

ice    →   led

Ice is a solid form of water. Water expands when it freezes due to hydrogen bonds thus making ice less density than water so it floats on it.

isomer    →   izomer

Isomers are compounds that have identical molecular formulae but differ in the nature or sequence of bonding of their atoms (structural isomerism) or in the arrangement of their atoms in space (stereoisomerism).

Lewis acid    →   Lewisova kiselina

Lewis acid is an agent capable of accepting a pair of electrons to form a coordinate bond.

conformation    →   konformacija

Conformation is one of the very large numbers of possible spatial arrangements of atoms that can be interconverted by rotation about a single bond in a molecule. The conformation of a molecule is not fixed, though one or another shape may be more likely to occur. There are two extreme cases:

Staggered conformation (antiperiplanar) is a conformation about a carbon-carbon single bond in which the atoms on one carbon are as far apart as possible from the atoms on an adjacent carbon.

Eclipsed conformation (syn-periplanar) is a conformation about a carbon-carbon single bond in which the atoms on one carbon are as close as possible to the atoms on an adjacent carbon.

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.

Lewis base    →   Lewisova baza

Lewis base is an agent capable of donating a pair of electrons to form a coordinate bond.

Lewis, Gilbert N.    →   Lewis, Gilbert N.

Gilbert Newton Lewis (1875-1946) is an American chemist whose theory of the electron pair fostered understanding of the covalent bond and extended the concept of acids and bases.