Editing Intermolecular force (section)

==Relative strength of forces==

{|class="wikitable"
!Bond type
!Dissociation energy<br />(kcal/mol)<ref name=Seyhan-Organic-Chemistry>{{cite book | vauthors = Eğe SN |title=Organic Chemistry: Structure and Reactivity |date=2004 |publisher=Houghton Mifflin Company |location=Boston |isbn=978-0-618-31809-4 |edition=5th | pages = 30–33, 67}}</ref>
!Dissociation energy
(kJ/mol)
!Note
|-
|Ionic lattice
|250–4000<ref name=Purdue-Lattice>{{cite web |title=Lattice Energies |url=http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch7/lattice.html |access-date=2014-01-21 | work = Division of Chemical Education | publisher = Purdue University }}</ref>
|1100–20000
|
|-
|Covalent bond
|30–260
|130–1100
|
|-
|[[Hydrogen bond]]
|1–12
|4–50
|About 5&nbsp;kcal/mol (21&nbsp;kJ/mol) in water
|-
|Dipole–dipole
|0.5–2
|2–8
|
|-
|London dispersion forces
|<1 to 15
|<4 to 63
|Estimated from the enthalpies of vaporization of hydrocarbons<ref name=Majer-Svoboda-enthalpy-vap>{{cite book | vauthors = Majer V, Svoboda V |title=Enthalpies of Vaporization of Organic Compounds |date=1985 |publisher=Blackwell Scientific |location=Oxford |isbn=978-0-632-01529-0}}</ref>
|}

This comparison is approximate. The actual relative strengths will vary depending on the molecules involved. For instance, the presence of water creates competing interactions that greatly weaken the strength of both ionic and hydrogen bonds.<ref>{{Cite book |last1=Alberts |first1=Bruce |display-authors=etal |url=https://www.worldcat.org/oclc/887605755 |title=Molecular biology of the cell |date=2015 |isbn=978-0-8153-4432-2 |edition=6th |publisher=[[Garland Science]] - [[Taylor & Francis]] |location=New York, NY |oclc=887605755 }}</ref> We may consider that for static systems, [[Ionic bonding]] and [[covalent bond]]ing will always be stronger than intermolecular forces in any given substance. But it is not so for big moving systems like [[enzyme]] molecules interacting with [[Substrate (chemistry)|substrate]] molecules.<ref>{{cite journal | vauthors = Savir Y, Tlusty T | title = Conformational proofreading: the impact of conformational changes on the specificity of molecular recognition | journal = PLOS ONE | volume = 2 | issue = 5 | pages = e468 | date = May 2007 | pmid = 17520027 | pmc = 1868595 | doi = 10.1371/journal.pone.0000468 | bibcode = 2007PLoSO...2..468S | doi-access = free }}</ref> Here the numerous intramolecular (most often - [[hydrogen bond]]s) bonds form an active intermediate state where the intermolecular bonds cause some of the [[covalent bond]] to be broken, while the others are formed, in this way enabling the thousands of [[Enzyme catalysis|enzymatic reactions]], so important for [[Organism|living organisms]].