CHEMISTRY GLOSSARY

debye    →   debye

Debye (D) is a common non-SI unit of dipole moment, named after the Dutch physical chemist Peter Debye (1884-1966). A charge separation equal to one electron charge placed one Ångstrom unit apart has a dipole moment of 4.8 D. In SI units, 1 D = 3.335 6409 52×10^-29 C m.

electron volt    →   elektronvolt

Electron volt (eV) is a non-SI unit of energy used in atomic and nuclear physics, equal to approximately 1.602 177×10^-19 J. The electron volt is defined as the kinetic energy acquired by an electron upon acceleration through a potential difference of 1 V.

angular momentum    →   moment količine gibanja

Angular momentum is a physical quantity defined for rotating motion (in analogy to momentum that is defined for linear motion). If a body rotates around a specified axis, its angular momentum equals

Where I is the rotational inertia concerning that axis and ω is the angular velocity of the body.

Angular momentum can also be defined for a point-like body concerning a specified origin (in that case, it is not necessary that the point-like body undergoes circular motion). Rotational inertia of the point-like body, concerning that origin equals:

Where m is the mass of the body and r is its distance from the origin.

emulsion    →   emulzija

Emulsion is a colloidal system in which the dispersed and continuous phases are both liquids (e.g. oil in water or water in oil). Such systems require an emulsifying agent to stabilize the dispersed particles.

eutectic    →   eutektik

Eutectic is a solid solution consisting of two or more substances and having the lowest freezing point of any possible mixture of these components.

Eutectic point is the lowest temperature at which the eutectic mixture can exist in a liquid phase. A liquid having the eutectic composition will freeze at a single temperature without a change of composition.

Fermi level    →   Fermijev nivo

Fermi level is the highest energy of occupied states in a solid at zero temperature. The Fermi level in conductors lies in the conduction band, in insulators it lies in the valence band, and in semiconductors it falls in the gap between the conduction band and the valence band. It was named after the Italian physicst Enrico Fermi (1901 - 1954).

artificial radioactive isotope    →   umjetni radioaktivni izotop

Artificial radioactive isotopes are formed when an atom is bombed with an accelerator or exposing it to slow moving neutrons in a nuclear reactor. In this way isotopes (radionuclides) are obtained which are non-existent in nature because of their unstability and radioactive transition into stable isotopes. Most important radioactive isotopes are:

Radioactive isotope of cobalt is formed when ordinary metal cobalt is bombed with neutrons in a nuclear reactor.

Radioactive isotope of phosphorus is formed when ordinary phosphorus is bombed with deuterons produced in cyclotron.

radioactive isotope of carbon is formed when a nitrogen is bombed with slow moving neutrons in a nuclear reactor. It is mostly used as a radioactive indicator.

fluorescence    →   fluorescencija

Fluorescence is a luminescence phenomenon in which electron returns to it's ground state almost instantaneously (less than 10^-8 second), and in which emission from a luminescent substance ceases when the exciting source is removed. Fluorescence is characterized by radiation emission in all directions.

frequency    →   frekvencija

Frequency (ν) is the number of cycles of a periodic phenomenon divided by time. Hertz (Hz) is the SI derived unit, with a special name, for frequency, equal to s^-1. It was named after the German scientist Heinrich Hertza (1857-1894).

gel    →   gel

Gels are colloids in which both dispersed and continuous phases have a three-dimensional network throughout the material, so that it forms a jelly-like mass (e.g. gelatine). One component may sometimes be removed to leave a rigid gel (e.g. heating silica gel).