# Functionality (chemistry) > Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Functionality_(chemistry) > Markdown URL: https://mediated.wiki/source/Functionality_(chemistry).md > Source: https://en.wikipedia.org/wiki/Functionality_(chemistry) > Source revision: 1252930431 > License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) {{Short description|Presence of functional groups within a molecule}} {| class="wikitable floatright" id="cxmwAQ" style="text-align:center; font-size:90%" width="20%" ! Monofunctional compounds |- | [[File:Methyl-Acetate Structural Formula V1.svg|120x120px|[Essigsäuremethylester](/source/Essigs%C3%A4uremethylester)]]
[Methyl acetate](/source/Methyl_acetate) |- | [[File:Thiophenol Structural Formula V1.svg|90x90px|[Thiophenol](/source/Thiophenol)]]
[Thiophenol](/source/Thiophenol) |- | [[File:Ethyl Amine Structural Formula V1.svg|105x105px|[Ethylamin](/source/Ethylamin)]]
[Ethylamine](/source/Ethylamine) |} {| class="wikitable floatright" id="cxmwHg" style="text-align:center; font-size:90%" width="20%" ! Difunctional compounds |- | [[File:Malonic Acid Structural Formula V1.svg|107x107px|[Malonsäure](/source/Malons%C3%A4ure)]]
[Malonic acid](/source/Malonic_acid) |- | 73x73px|2-Aminoethanol
[Ethanolamine](/source/Ethanolamine) |- | [[File:Glycine Structural Formula V1.svg|90x90px|[Glycin](/source/Glycin)]]
[Glycine](/source/Glycine) |} {| class="wikitable floatright" id="cxmwOw" style="text-align:center; font-size:90%" width="20%" ! Trifunctional compounds |- | [[File:Glycerine Structural Formula V1.svg|100x100px|[Glycerin](/source/Glycerin)]]
[Glycerol](/source/Glycerol) |- | [[File:(R)-Cysteine Structural Formula V1.svg|91x91px|[(''R'')-Cystein](/source/Cystein)]]
[(''R'')-Cysteine](/source/Cysteine) |} In [chemistry](/source/chemistry), '''functionality''' is the presence of [functional group](/source/functional_group)s in a [molecule](/source/molecule). A '''monofunctional''' molecule possesses one functional group, a '''[bifunctional](/source/bifunctional)''' (or '''difunctional''') two, a '''trifunctional''' three, and so forth. In [organic chemistry](/source/organic_chemistry) (and other fields of chemistry), a molecule's functionality has a decisive influence on its [reactivity](/source/Reactivity_(chemistry)). In [polymer chemistry](/source/polymer_chemistry), the functionality of a [monomer](/source/monomer) refers to its number of [polymerizable](/source/Polymerization) groups, and affects the formation and the degree of [crosslinking](/source/Cross-link) of [polymers](/source/Polymer). == In organic chemistry and material science == In organic chemistry, functionality is often used as a synonym for [functional group](/source/functional_group). For example, a [hydroxyl group](/source/hydroxyl_group) can also be called a HO-function.Kurt Peter C. Vollhardt, [Neil Eric Schore](/source/Neil_Eric_Schore): ''Organische Chemie'', S. 73 ({{Google books|3eIXefCwsEMC||page=74}}).Riedel: ''Moderne Anorganische Chemie'' von Christoph Janiak, S. 401 ({{Google books|bW7cxciPCv4C||page=401}}). ''Functionalisation'' means the introduction of functional groups, for example * the functionalisation of a surfaceAlexander Langner, Anthony Panarello, Sandrine Rivillon, Oleksiy Vassylyev, Johannes G. Khinast, Yves J. Chabal: ''Controlled Silicon Surface Functionalization by Alkene Hydrosilylation'', [J. Am. Chem.](/source/Journal_of_the_American_Chemical_Society) (e.g. [silanization](/source/silanization) for the specific modification of the [adhesion](/source/adhesion) of a [surface](/source/surface_science)) * the functionalization of [nanoparticle](/source/nanoparticle)s of a metal or metal oxide to stabilize such nanoparticlesMarie-Alexandra Neouze, Ulrich Schubert: Surface Modification and Functionalization of Metal and Metal Oxide Nanoparticles by Organic Ligands, Monatsh. or * the so-called [C-H functionalization](/source/Carbon%E2%80%93hydrogen_bond_activation),Dirk Steinborn: ''Grundlagen der metallorganischen Komplexkatalyse'', S. 305 ({{Google books|01bZ7l-ISJ8C||page=239}} which means the substitution of a C-H bond by a functional group, bonded at the same carbon atom == In polymer chemistry == According to [IUPAC](/source/International_Union_of_Pure_and_Applied_Chemistry), the functionality of a monomer is defined as the number of [bonds](/source/Chemical_bond) that a monomer's [repeating unit](/source/repeating_unit) forms in a polymer with other monomers. Thus in the case of a functionality of ''f'' = 2 a linear polymer is formed by polymerizing (a [thermoplastic](/source/thermoplastic)). Monomers with a functionality ''f'' ≥ 3 lead to a branching point, which can lead to [cross-linked](/source/cross-linked) polymers (a [thermosetting polymer](/source/thermosetting_polymer)). Monofunctional monomers do not exist as such molecules lead to a [chain termination](/source/chain_termination).Eintrag zu ''functionality, f of a monomer''. From the average functionality of the used monomers the reaching of the [gel point](/source/gel_point) can be calculated as a function of reaction progress.Koltzenburg: ''Polymere: Synthese, Eigenschaften und Anwendungen'', S. 187 ({{Google books|DSckBAAAQBAJ||page=188}}). This reference is being translated to English as "Polymer Chemistry" by the same authors, to appear in September 2017. See [https://www.springer.com/us/book/9783662492772] Side reactions may increase or decrease the functionality.Hans-Georg Elias: ''Makromoleküle: Chemische Struktur und Synthesen'', S. 468 und 477 ({{Google books|NYN9xJ47LmEC||page=468}}). However, IUPAC definition and the use of the term in organic chemistry differ with respect to the functionality of a double bond.{{GoldBookRef |title=chemical functionality |file=CT07503 }} In polymer chemistry, a double bond possesses a functionality of two (because two points of contact for further polymer chains are present, on each of the two adjacent carbon atoms), while in organic chemistry the double bond is a functional group and thus has a functionality of one. == References == {{Portal|Chemistry}} Category:Functional groups --- Adapted from the Wikipedia article [Functionality (chemistry)](https://en.wikipedia.org/wiki/Functionality_(chemistry)) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Functionality_(chemistry)?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.