Reaction nucleaire — Réaction nucléaire Une réaction nucléaire est une transformation d un ou plusieurs noyaux atomiques, elle se distingue d une réaction chimique qui concerne les électrons ou les liaisons entre les atomes. Dans une réaction nucléaire, deux noyaux… … Wikipédia en Français
Réaction nucléaire — Une réaction nucléaire est une transformation d un ou plusieurs noyaux atomiques, elle se distingue d une réaction chimique qui concerne les électrons ou les liaisons entre les atomes. Dans une réaction nucléaire, deux noyaux atomiques entrent en … Wikipédia en Français
Value Added Tax-free Exports from the Channel Islands — are exports of goods from the Channel Islands on which value added tax (VAT) is not levied. In recent years, companies in the United Kingdom have expressed concern at the competition thereby offered to their goods on which VAT is… … Wikipedia
reaction, heat of — Amount of heat that must be added or removed during a chemical reaction to keep all substances involved at the same temperature. If it is positive (heat must be added), the reaction is endothermic; if it is negative (heat is given off), the… … Universalium
Reaction rate — Iron rusting a chemical reaction with a slow reaction rate. Wood … Wikipedia
reaction — 1. The response of a muscle or other living tissue or organism to a stimulus. 2. The color change effected in litmus and certain other organic pigments by contact with substances such as acids or alkalies; also the property that such substances… … Medical dictionary
Reaction — A reversal in the movement of a security s price. Reaction is most often associated with a downward movement in the price of a security after a period of upward movement, as investors sell off shares or decrease the volume of buy orders for fear… … Investment dictionary
acid–base reaction — ▪ chemistry Introduction a type of chemical process typified by the exchange of one or more hydrogen ions, H+, between species that may be neutral (molecules, such as water, H2O; or acetic acid, CH3CO2H) or electrically charged (ions, such… … Universalium
electrochemical reaction — ▪ chemistry Introduction any process either caused or accompanied by the passage of an electric current and involving in most cases the transfer of electrons between two substances one a solid and the other a liquid. Under ordinary… … Universalium
oxidation–reduction reaction — ▪ chemical reaction Introduction also called redox reaction any chemical reaction in which the oxidation number of a participating chemical species changes. The term covers a large and diverse body of processes. Many oxidation– reduction… … Universalium
Nuclear chain reaction — A possible nuclear fission chain reaction. 1. A uranium 235 atom absorbs a neutron, and fissions into two new atoms (fission fragments), releasing three new neutrons and a large amount of binding energy. 2. One of those neutrons is absorbed by an … Wikipedia