CHEMISTRY GLOSSARY

neutrino    →   neutrino

Neutrino is a stable elementary particle in the lepton family. Neutrinos have zero (or at least near-zero) rest mass and spin 1/2.

neutron    →   neutron

Neutron is an elementary particle on spin 1/2 and zero charge. The free neutron has an average lifetime of 887 seconds. Neutrons and protons, which are collectively called nucleons, are the constituents of the nucleus.

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.

nonelectrolyte    →   neelektrolit

Nonelectrolytes are substances which in solutions do not dissociate into ions and they do not conduct electric current.

oersted    →   ersted

Oersted (Oe) is a non-SI unit of magnetic field (H), equal to 79.577 471 57 A/m. The unit was named after the Danish physicist and chemist Hans Christian Oersted (1777-1851).

ohm    →   om

Ohm (Ω) is the SI derived unit of electric resistance. The ohm is the electric resistance between two points of a conductor when a constant difference of potential of one volt, applied between these two points, produces in this conductor a current of one ampere, this conductor not being the source of electromotive force (Ω = V/A). The unit was named after the German physicist Georg Simon Ohm (1789-1854).

paramagnetism    →   paramagnetizam

Paramagnetism is a type of magnetism characterised by a positive magnetic susceptibility, so that the material becomes weakly magnetised in the direction of an external field. The magnetisation disappears when the field in removed.

Fajans’ rules    →   Fajansova pravila

Fajans’ rules, formulated by American chemist of Polish origin. Kazimierz Fajans (1887-1975), indicating the extent to which an ionic bond has covalent character caused by polarisation of the ions. Covalent character is more likely if:

1. the charge of the ions is high;

2. the positive ion is small or the negative ion is large;

3. the positive ion has an outer electron configuration that is not a noble- gas configuration.

ferrite    →   ferit

Ferrites are ceramic materials of the nominal formula MO·Fe₂O₃, where M is a divalent metal (Co, Mn, NI, or Zn). The ferrites show either ferrimagnetism or ferromagnetism, but are not electrical conductors, and they are used in high-frequency circuits as magnetic cores, in rectifiers on memory and record tapes, and various related uses in radio, television, radar, computers, and automatic control systems.

ferromagnetism    →   feromagnetizam

Ferromagnetism is a type of magnetism in which the magnetic moments of atoms in a solid are aligned within domains which can in turn be aligned with each other by a weak magnetic field. The total magnetic moment of a sample of the substance is the vector sum of the magnetic moments of the component domains. In an unmagnetized piece of ferromagnetic material the magnetic moments of the domains themselves are not aligned; when an external field is applied those domains that are aligned with the field increase in size at the expense of the others. Ferromagnetic materials can retain their magnetisation when the external field is removed, as long as the temperature is below a critical value, the Curie temperature. They are characterised by a large positive magnetic susceptibility.