CHEMISTRY GLOSSARY

radiography    →   radiografija

Radiography is nondestructive method of internal examination in which metal objects are exposed to a beam of X-ray or gamma radiation. Differences in thickness, density, or absorption caused by internal defects or inclusions are apparent in the shadow image produced on a fluorescent screen or photographic film placed behind the object.

Raman effect    →   Ramanov efekt

Raman effect is a type of scattering of electromagnetic radiation in which light suffers a change in frequency and a change in phase as it passes through a material medium. Named according to the Indian physicist C. V. Raman (1889-1970). The intensity of Raman scattering is about one-thousandth of that in Rayleigh scattering in liquids.

refractive index    →   indeks loma

For a non-absorbing medium, refractive index (n) is the ratio of the velocity of electromagnetic radiation (light) in vacuum to the phase velocity of radiation of a specified frequency in the medium.

sievert    →   sivert

Sievert (Sv) is the SI derived unit of dose equivalent when the absorbed dose of ionising radiation multiplied by the stipulated dimensionless factors is 1 J/kg. It was named after the Swedish physicst Rolf Sievert (1896-1966).

candela    →   kandela

Candela (cd) is the SI base unit of luminous intensity.

The candela is the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency 540×10¹² Hz and that has a radiant intensity in that direction of 1/683 watt per steradian.

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).

symmetry    →   simetrija

Symmetry is the property of a molecule, whereby the molecule has the same observed physical structure and appearance, when viewed from different orientations in space.

Tyndall’s effect    →   Tyndallov efekt

Tyndall’s effect occurs when light disperses on colloid particles. This phenomenon can be seen when a ray of light enters in dark room through a small hole. In the beam some dust particles of colloid dimensions can be seen sparkling.

van der Waals’ force    →   van der Waalsova sila

Van derWaals’ force is the weak attractive force between two molecules which arises from electric dipole interactions. It can lead to the formation of stable but weakly bound dimer molecules or clusters. They are named after the Dutch physicist Johannes van der Waals (1837-1923).

vertical ionisation energy    →   vertikalna energija ionizacije

Vertical ionisation energy is the energy required to remove an electron from an atom, molecule, or ion in the gas phase without moving any nuclei. The vertical ionisation energy is greater than or equal to the adiabatic ionisation energy.