(physics) A nuclear reaction in which particles produced by the fission of one atom trigger fissions of other atoms. / (figuratively) A series of events, each one causing or influencing the next.

(chemistry) Either the oxidation or the reduction component of a redox reaction

A process such as the fission of an atomic nucleus, or the fusion of one or more atomic nuclei and/or subatomic particles in which the number of protons and/or neutrons in a nucleus changes; the reaction products may contain a different element or a different isotope of the same element.

(chemistry) The reaction of a Grignard reagent (an organo-magnesium halide) with aldehydes or ketones to form secondary or tertiary alcohols

(idiomatic) An instantaneous reaction made without thought.

(chemistry) a reaction in which one functional group is replaced with another

(chemistry) a bimolecular nucleophilic substitution reaction

(chemistry) a unimolecular nucleophilic substitution reaction

(chemistry) the ordered set of individual reactions whose overall effect is given by a chemical equation

(chemistry) a reaction in which radicals are added to both sides of a double or triple bond