CHEMISTRY GLOSSARY

impedance    →   impedancija

Impedance is the analogue of the resistance or resistivity when applied to alternating current. That is, it is a measure of a material’s inability to carry the electrical current. In many materials the impedance varies as the frequency of the applied electrical potential changes, due to the properties of the conducting liquid or solid. In electrochemistry, the impedance of the electrodes is also frequency dependent.

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monochromator    →   monokromator

Monochromator (from the Greek words mono and chroma meaning single and colour) is an optical device based on dispersion of light by one or more prisms or diffraction gratings into its constituent wavelengths, which are utilized in turn.

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Buchner funnel    →   Buchnerov lijevak

Büchner funnel is one device used for pressure assisted filtration. Buchner funnel is a cylindrical porcelain filtering funnel (glass and plastic funnels are also available) that has a perforated plate on which the flat filter paper is placed. A vacuum in the flask underneath the filter allows atmospheric pressure on the sample to force the liquid through the filter paper. It is named after the German chemist Ernst Wilhelm Büchner (1850-1925) who designed this funnel in 1885.

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caesium    →   cezij

Caesium was discovered by Robert Bunsen and Gustav Kirchhoff (Germany) in 1860. The origin of the name comes from the Latin word caesius meaning sky blue or heavenly blue. It is very soft, light grey, ductile metal. Reacts readily with oxygen. Reacts explosively with water. Caesium is found in pollucite [(Cs₄Al₄Si₉O₂₆)·H₂O] and as trace in lepidolite. Used as a ’getter’ to remove air traces in vacuum and cathode-ray tubes. Also used in producing photoelectric devices and atomic clocks. Since it ionises readily, it is used as an ion rocket motor propellant.

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capacitor    →   kondenzator

Capacitor is a device that stores electric charges. The symbol for a capacitor in electric circuit schemes is —| |—.

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cathode    →   katoda

Cathode is a negative electrode of an electrolytic cell to which positively charged ions (cations) migrate when a current is passed as in electroplating baths.

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In a primary or secondary cell (battery or accumulator) the cathode is the electrode that spontaneously becomes negative during discharge, and form which therefore electrons emerge.

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In vacuum electronic devices electrons are emitted by the cathode and flow to the anode.

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MOSFET    →   MOSFET

MOSFET (metal oxide field effect transistor) is a semiconductor device which can be used as an ion selective electrode.

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pyrotechnics    →   pirotehnika

Pyrotechnics include the production of fireworks, devices and mixtures for illumination using easily inflammable and explosive chemicals.

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selenide    →   selenid

Selenides are compounds having the structure R-Se-R (R not equal to H). They are thus selenium analogues of ethers. Also used for metal salts of H₂Se.

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silanes    →   silani

Silanes are saturated silicon hydrides, analogues of the alkanes (compounds of the general formula Si_nH_2n+2).

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