What is Substitution reaction?
[[File:SubstitutionReaction.svg|thumb|right|350px|An example of a substitution reaction. Here, one [[hydrogen]] atom in [[methane]] is substituted by a [[chlorine]] atom]] In [[chemistry]], a '''substitution reaction''' happens when an [[atom]] or a group of atoms is replaced by a different one. Substitution reactions can be of many different types. In [[organic chemistry]], the main ones are [[nucleophilic substitution]] and [[electrophilic substitution]]. These take their names from [[electrophile]]s and [[nucleophile]]s. However, substitution reactions can also happen under other conditions. For example, [[photochemistry|photochemical]] reactions (reactions that use light instead of heat) are used to put [[halogen]]s in a [[molecule]]. Another example is using [[free radical]]s. Choosing the correct [[solvent]] and [[temperature]] conditions is very important to make sure that the reaction happens. Sometimes an [[elimination reaction]] can happen instead. The [[product (chemistry)|product]] of a substitution reaction is often called a substituted molecule. For example, [[phenol]] can be called a substituted [[benzene]]. [[Category:Chemical reactions]] {{chem-stub}}