"functional group." YourDictionary, n.d. Web. 14 January 2019. <https://www.yourdictionary.com/functional-group>.
functional group. (n.d.). Retrieved January 14th, 2019, from https://www.yourdictionary.com/functional-group
An atom or group of atoms that replaces hydrogen in an organic compound. Functional groups define the structure of a family of compounds and determine its properties. The carboxyl and hydroxyl groups are functional groups that define the compounds they are part of as organic acids and alcohols, respectively.