Editing Rotamer (section)

===Nomenclature===
Naming alkanes per standards listed in the [[IUPAC Gold Book]] is done according to the [[Klyne–Prelog system]] for specifying angles (called either torsional or [[dihedral angles]]) between substituents around a single bond:<ref name =torsion>{{GoldBookRef|title=torsion angle|file=T06406| accessdate = 2015-10-29 }}</ref>
[[Image:Synantipericlinal.svg|200px|right|syn/anti peri/clinal]]
* a torsion angle between 0° and ±90° is called '''syn'''  (s)
* a torsion angle between ±90° and 180° is called '''anti''' (a)
* a torsion angle between 30° and 150° or between −30° and −150° is called '''clinal''' (c)
* a torsion angle between 0° and ±30° or ±150° and 180° is called '''periplanar''' (p)
* a torsion angle between 0° and ±30° is called '''[[Anti-periplanar|synperiplanar]]''' (sp), also called '''syn-''' or '''cis-''' conformation
* a torsion angle between 30° to 90° and −30° to −90° is called '''synclinal''' (sc), also called '''gauche''' or '''skew'''<ref name="GoldbookGauche">{{GoldBookRef|title=gauche|file=G02593| accessdate = 2008-02-27 }}</ref> 
* a torsion angle between 90° and 150° or −90° and −150° is called '''anticlinal''' (ac)
* a torsion angle between ±150° and 180° is called '''[[Anti-periplanar|antiperiplanar]]''' (ap), also called '''anti-''' or '''trans-''' conformation
[[Strain (chemistry)#Torsional strain|Torsional strain]] or "Pitzer strain" refers to resistance to twisting about a bond.