1.2 Intermolecular forces of attraction. Hydrogen bonds and biological meaning.

Hydrogen bonding

Hydrogen bonding is when a hydrogen atom bonds with a highly electronegative atom (e.g., Fluorine (F), Oxygen (O) and Nitrogen (N)) leading to a highly polar covalent. This causes a very strong dipole-dipole bond which we call a hydrogen bond. 

Biologically Hydrogen bonding hold DNA together determines the 3D protein structure and it is responsible for water unique soluble capacities.

Ion- dipole forces

Ion- dipole force - This is the force between an ion and a neutral molecule that has a dipole.

                      - Stronger than H-bonding

dipole-dipole forces

Dipole-Dipole force - Caused by separation of charge between bonded atoms. The greater the difference in electronegativity, the stronger the bond.

                      - H2O has a large permanent dipole.

 London dispersion forces.

London dispersion force - Induced Dipole-Dipole forces are weak forces caused by tiny momentary dipoles between atoms. The larger the molecule, the larger the temporary dipole and thus the larger the force.

VdW forces is the term used to cover the;

- forces between permanent dipoles

- forces between permanent dipole + induced dipole.

- forces between induced dipoles