Vander waals forces and its significance

vander waals force , its type and its significance.

1. Vander Waals Forces and Its Significance By -: Lovnish Thakur(IBT-1 ST SEM) Enrollment No. -: ASU2014010100099 Presentation-:U4P1 Course-: Chemistry for biologist(102)

2. Vander Waals force It is the sum of the attractive or repulsive forces between molecules. These were named after -: Johannes Diderik van der Waals

3. Its main characteristics are:- They are weaker than normal covalent ionic bonds. Van der Waals forces are additive and cannot be saturated. They have no directional characteristic. They are all short - range forces and hence only interactions between nearest need to be considered instead of all the particles. The greater is the attraction if the molecules are closer due to Van der Waals forces. Van der Waals forces are independent of temperature except dipole - dipole interactions.

4. These includes-: force between two permanent dipoles ( Keesom force) force between a permanent dipole and a corresponding induced dipole (Debye force) force between two instantaneously induced dipoles (London dispersion force).

5. Dipole-Dipole Two polar molecules align so that d + and d - are matched (electrostatic attraction ). Ex: ethane (C 2 H 6 ) vs. fluromethane (CH 3 F) www.bbc.co.uk

6. Dipole-Induced Dipole A dipole can induce (cause) a temporary dipole to form in a non-polar molecule The molecules then line up to match d + and d - charges www.meta-synthesis.com

7. Dispersion Forces A temporary dipole forms in a non-polar molecule which leads to a temporary dipole to form in another non-polar molecule. Dispersion is the only intermolecular attraction that occur between non-polar molecules sciencejl.blogspot.com

8. SIGNIFICANCE

9. In Protein folding www.intechopen.com Vander waals interaction is the another important bonding type that helps stabilizing the protein structure. In the coiled-coil protein, there is interaction between side chain in alpha helix . If these repeating residues are hydrophobic, such as leucine , van der waals interaction will be formed to stabilize this protein structure.

10. Graphenes Bonding Forces in Graphite Weak forces between graphenes suggest that they are the van der Waals Forces.

11. In polymer formation Many polymeric chain are cross linked by vander waals force and get stable. www.m2polymer.com

12. Used by some animal Gecko lizard use these forces to climb on the walls. Some other animal use animal to walk on water. en.wikipedia.org dieffi.deviantart.com

13. In modern technology In May 2014, DARPA demonstrated the latest iteration of its Geckskin by having a 100kg researcher (saddled with 20kg of recording gear) scale an 8m tall glass wall using only two climbing paddles. Tests are ongoing, but DARPA hopes one day to make the technology available for military use, giving soldiers Spider Man-like abilities in urban combat

14. www.wired.com

15. References http://en.wikibooks.org/wiki/Structural_Biochemistry/Chemical_Bonding/Van_der_Waals_interaction antoine.frostburg.edu/ chem / senese /.../h-bonding-vs-london-forces.shtml en.wikipedia.org/wiki/ Van_der_Waals_force chemwiki.ucdavis.edu › ... › Intermolecular Forces przyrbwn.icm.edu.pl/APP/PDF/112/a112z308.pdf