CHEMISTRY GLOSSARY
free radical → slobodni radikal
Free radical is a molecular fragment having one or more unpaired electrons, usually short-lived and highly reactive. They can be produced by photolysis or pyrolysis in which a bond is broken without forming ions. In formulas, a free radical is conventionally indicated by a dot (·CH3, ·SnH3, ·Cl). Free radicals are known to be formed by ionising radiation and thus play a part in deleterious degradation effects that occur in irradiated tissue. They also act as initiators or intermediates in oxidation, combustion, photolysis, and polymerisation.
freon → freon
Freon (chlorofluorocarbon, CFC) a type of compound in which some or all of the hydrogen atoms of hydrocarbon (usually an alkane) have been replaced by chlorine and fluorine atoms. Most CFC are chemically uncreative and are stable at high temperatures. They are used as aerosol propellants, refrigerants, and solvents, and in the manufacture of rigid packaging foam. CFC because of their chemical inertness, can diffuse unchanged into the upper atmosphere. Here, photochemical reactions cause them to break down and react with ozone. For his reason, their use has been discouraged.
positive pole → pozitivni pol
Positive pole is that half-cell in the electrochemical cell which has the most positive electrode potential.
potential of decomposition → napon razlaganja
Potential of decomposition of some system is the least potential which should be applied so that electrolysis should occur.
fuel cell → gorivi članak
Fuel cell is a device that converts chemical energy into electrical energy. It is different from a battery in that the energy conversion continues as long as fuel and oxidising agent are fed to the fuel cell; that is, in principle indefinitely. (A battery is manufactured with a limited amount of chemicals, and it is exhausted when all the chemicals have reacted.) It is a galvanic cell where spontaneous chemical reactions occur at the electrodes. The fuel is oxidised at the anode, and the oxidising agent (almost always oxygen or air) is reduced at the cathode. Presently, the most commonly used fuel is hydrogen. More conventional fuels (e.g., petrol or natural gas) must be converted (reformed) into hydrogen before they can be utilised in a fuel cell.
Some fuel cells employ an aqueous solution as electrolyte, that can be either acidic or basic (alkaline), or an ion-exchange membrane soaked in aqueous solution can act as the electrolyte. These fuel cells operate at relatively low temperatures (from room temperature to not much above the boiling point of water). Some fuel cells employ molten salts (especially carbonates) as electrolytes and have to operate at temperatures of several hundred degrees centigrade (Celsius). Others employ ionically conductive solids as electrolyte and must operate close to 1 000 °C.
gamma radiation → gama-zračenje
Gamma radiation is electromagnetic radiation of extremely short wavelength. Gamma radiation ranges in energy from about 10-15 J to 10-10 J (10 keV to 10 MeV) (wavelength less than about 1 pm). Gamma rays are emitted by excited atomic nuclei during the process of passing to a lower excitation state.
Gamma rays are extremely penetrating and are absorbed by dense materials like lead and uranium. Exposure to gamma radiation may be lethal.
quantum numbers → kvantni brojevi
Quantum numbers describe the distance, shape and orientation of electronic orbitals.
Citing this page:
Generalic, Eni. "Valentni elektron." Croatian-English Chemistry Dictionary & Glossary. 29 June 2022. KTF-Split. {Date of access}. <https://glossary.periodni.com>.
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