CHEMISTRY GLOSSARY

osmometry    →   osmometrija

Osmometry is a determination of the average molecular weight of a dissolved substance from measurements of osmotic pressure.

oxonium ion    →   oksonijev ion

Oxonuim ion (H₃O⁺) is formed when a molecule of water binds with a proton.

electron affinity    →   elektronski afinitet

Electron affinity (E_A) is the energy change occurring when an atom or molecule gains an electron to form a negative ion. For an atom or molecule X, it is the energy released for the electron-attachment reaction

This is often measured in electronvolts. Alternatively, the molar enthalpy change, ΔH, can be used.

electronegativity    →   elektronegativnost

Electronegativity is a parameter originally introduced by L. Pauling which describes, on a relative basis, the power of an atom to attract electrons. For example, in hydrogen chloride, the chlorine atom is more electronegative than the hydrogen and the molecule is polar, with a negative charge on the chlorine atom.

There are various ways of assigning values for the electronegativity of an element. Pauling electronegativities are based on bond dissociation energies using a scale in which fluorine, the most electronegative element, has the value 4 and francium, the lowest electronegative element, has the value 0.7.

enantiomer    →   enantiomer

Enantiomers are a chiral molecule and its non-superposable mirror image. The two forms rotate the plane of polarised light by equal amounts in the opposite directions. Also called optical isomers.

energy    →   energija

Energy (E, U) is the characteristic of a system that enables it to do work. Like work itself, it is measured in joules (J).

The internal energy of a body is the sum of the potential energy and the kinetic energy of its component atoms and molecules.

Potential energy is the energy stored in a body or system as a consequence of its position, shape, or state (this includes gravitation energy, electrical energy, nuclear energy, and chemical energy).

Kinetic energy is the energy of motion and is usually defined as the work that will be done by a body possessing the energy when it is brought to rest. For a body of mass m having a speed v, the kinetic energy is mv²/2. Kinetic energy is most clearly exhibited in gases, in which molecules have much greater freedom of motion than in liquids and solids.

In an isolated system energy can be transferred from one form to another but the total energy of the system remains constant.

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.

propagation    →   propagacija

Propagation is the step in a polymerization mechanism, where new monomer molecules are added to the growing polymer chain in the free radical process.

protein    →   bjelančevina

Proteins are natural organic compounds of animal or herbal origin, essential in diet. They are natural polymers developed from a crowd of interconnecting monomers of amino acids, with relative molecular masses amounting up to a few million.

enzyme    →   enzim

Enzyme is a protein that acts as a catalyst in biochemical reactions. Each enzyme is specific to a particular reaction or a group of similar reactions. Many require the association of certain nonprotein cofactors in order to function. The molecule undergoing a reaction (the substrate) binds to a specific active site on the enzyme molecule to form a short-lived intermediate: this greatly increases (by a factor of up to 10²⁰) the rate at which the reaction proceeds to form the product.