Editing Macromolecule (section)

== Definition ==
{{Quote box
 |title = [[International Union of Pure and Applied Chemistry|IUPAC]] definition
 |quote = '''Macromolecule'''<br/>'''Large molecule'''

A molecule of high relative molecular mass, the structure of which essentially<br/>comprises the multiple repetition of units derived, actually or conceptually, from<br/>molecules of low relative molecular mass.

;Notes

1. In many cases, especially for synthetic polymers, a molecule can be regarded<br/>as having a high relative molecular mass if the addition or removal of one or a<br/>few of the units has a negligible effect on the molecular properties. This statement<br/>fails in the case of certain macromolecules for which the properties may be<br/>critically dependent on fine details of the molecular structure.<br/>
2. If a part or the whole of the molecule fits into this definition, it may be described<br/>as either ''macromolecular'' or ''polymeric'', or by ''polymer'' used adjectivally.<ref>{{cite journal|title=Glossary of basic terms in polymer science (IUPAC Recommendations 1996)|journal=[[Pure and Applied Chemistry]]|date=1996|volume=68|issue=12|pages=2287–2311|doi=10.1351/pac199668122287|url=http://pac.iupac.org/publications/pac/pdf/1996/pdf/6812x2287.pdf|last1=Jenkins|first1=A. D|last2=Kratochvíl|first2=P|last3=Stepto|first3=R. F. T|last4=Suter|first4=U. W|s2cid=98774337|access-date=2013-07-27|archive-date=2016-03-04|archive-url=https://web.archive.org/web/20160304041907/http://pac.iupac.org/publications/pac/pdf/1996/pdf/6812x2287.pdf|url-status=dead}}</ref> 
}}
The term ''macromolecule'' (''[[wikt:macro-#Prefix|macro-]]'' + ''molecule'') was coined by [[Nobel Prize|Nobel laureate]] [[Hermann Staudinger]] in the 1920s, although his first relevant publication on this field only mentions ''high molecular compounds'' (in excess of 1,000 atoms).<ref>{{cite journal|author1=Staudinger, H. |author2=Fritschi, J. |title=Über Isopren und Kautschuk. 5. Mitteilung. Über die Hydrierung des Kautschuks und über seine Konstitution|doi=10.1002/hlca.19220050517|date=1922|journal=Helvetica Chimica Acta|volume=5|issue=5|pages=785|url=https://zenodo.org/record/1426825 }}</ref> At that time the term ''polymer'', as introduced by [[Jöns Jakob Berzelius|Berzelius]] in 1832, had a different meaning from that of today: it simply was another form of [[isomerism]] for example with [[benzene]] and [[acetylene]] and had little to do with size.<ref name=Jensen>{{cite journal|author1-link=William B. Jensen|doi=10.1021/ed085p624|title=The Origin of the Polymer Concept|date=2008|last1=Jensen|first1=William B.|journal=Journal of Chemical Education|volume=85|pages=624|issue=5|bibcode = 2008JChEd..85..624J }}</ref>

Usage of the term to describe large molecules varies among the disciplines. For example, while [[biology]] refers to macromolecules as the four large molecules comprising living things, in [[chemistry]], the term may refer to aggregates of two or more molecules held together by [[intermolecular force]]s rather than [[covalent bond]]s but which do not readily dissociate.<ref>van Holde, K.E. (1998) ''Principles of Physical Biochemistry'' Prentice Hall: New Jersey, {{ISBN|0-13-720459-0}}</ref>

According to the standard [[IUPAC]] definition, the term ''macromolecule'' as used in polymer science refers only to a single molecule. For example, a single polymeric molecule is appropriately described as a "macromolecule" or "polymer molecule" rather than a "polymer," which suggests a [[Chemical substance|substance]] composed of macromolecules.<ref>{{cite journal|url=http://www.iupac.org/reports/1996/6812jenkins/6812basicterms.pdf|journal=Pure and Applied Chemistry|volume=68|page=2287|date=1996|author=Jenkins, A. D.|title=Glossary of Basic Terms in Polymer Science|doi=10.1351/pac199668122287|last2=Kratochvíl|first2=P.|last3=Stepto|first3=R. F. T.|last4=Suter|first4=U. W.|issue=12|s2cid=98774337 |url-status=dead|archive-url=https://web.archive.org/web/20070223103549/http://www.iupac.org/reports/1996/6812jenkins/6812basicterms.pdf|archive-date=2007-02-23}}</ref>

Because of their size, macromolecules are not conveniently described in terms of [[stoichiometry]] alone. The structure of simple macromolecules, such as homopolymers, may be described in terms of the individual monomer subunit and total [[molecular mass]]. Complicated biomacromolecules, on the other hand, require multi-faceted structural description such as the hierarchy of structures used to describe [[proteins]]. In [[British English]], the word "macromolecule" tends to be called "'''high polymer'''".