CHEMISTRY GLOSSARY

point-like object    →   materijalna točka

Point-like object is an expression, usual in kinematics: a point-like object (or a particle) is an object with dimensions, which can be neglected while considering its motion.

polar covalent bond    →   polarna kovalentna veza

Polar covalent bond is a covalent bond in which the electrons are not equally shared because one atom attracts them more strongly than the other

polar solvent    →   polarno otapalo

Polar solvent is a liquid with polar molecules which dissolves polar compounds, because the charges on the endings of the solvent’s molecules attract the elements from ion crystals.

hybridization    →   hibridizacija

Hybridization is an internal linear combination of atomic orbitals, in which the wave functions of the atomic orbitals are added together to generate new hybrid wave functions. The new orbitals which are formed are hybrids of the originals and have properties (shape, size and energy) that are somewhere in between.

hydration    →   hidratacija

Hydration is addition of water or the elements of water (i.e. H and OH) to a molecular entity. The term is also used in a more restricted sense for the process:

hydrogen    →   vodik

Hydrogen was discovered by Sir Henry Cavendish (England) in 1766. The origin of the name comes from the Greek words hydro and genes meaning water and generate. It is colourless, odourless gas, burns and forms explosive mixtures in air. Reacts violently with oxidants. Hydrogen is the most abundant element in the universe. Commercial quantities of hydrogen are produced by reacting superheated steam with methane or carbon. In lab work from reaction of metals with acid solutions or electrolysis. Most hydrogen is used in the production of ammonia and in metal refining. Also used as fuel in rockets. Its two heavier isotopes (deuterium and tritium) used respectively for nuclear fusion.

hydrogen bond    →   vodikova veza

Hydrogen is a bond formed by a hydrogen atom to an electronegative atom, and is denoted by dashed lines H-X---H-B. A hydrogen atom covalently bound to an oxygen (electronegative atom) has a significant positive charge and can form a weak bond to another electronegative atom.

polarised light    →   polarizirana svjetlost

Polarised light is light whose electromagnetic waves oscillate only in one flat vertical on expansion of the direction of radiation.

polymorphic transition    →   polimorfni prijelaz

Polymorphic transition is a reversible transition of a solid crystalline phase at a certain temperature and pressure to another phase of the same chemical composition with a different crystal structure. For examples, the transitions of quartz (SiO₂) at 1 143 K to tridymite, and at 1 743 K to cristobalite.

hydrolysis    →   hidroliza

Hydrolysis is a chemical reaction in which water reacts with another substance to form two or more new substances. This involves ionisation of the water molecule, as well as splitting of the compound hydrolysed, e.g.

Examples are conversion of starch to glucose by water in the presence of suitable catalysts and a reaction of the ions of a dissolved salt to form various products, such as acids, complex ions, etc.