Biological Molecules and Intermolecular Forces

• Stronger than dipole-dipole interactions
• Electrostatic attraction between oppositely charged ions.
• Holds ions together in salt (NaCl)
• Contributes to enzyme active sites and protein stability.

When a charged ion is attracted to a polar molecule. The polar molecule has a partially charged side, which pulls on the oppositely charged ion.

• Between polar molecules
containing N, O, or F
• Accounts for the properties of water: high solubility of polar and ionic substances, cohesion, adhesion, high surface tension, capillarity, high specific heat capacity, and high specific heat of vaporization.
• Hydrogen bonding within proteins in
spider silk contributes to its strength.

A strong type of dipole interaction that happens when hydrogen (H) is bonded to nitrogen (N) or oxygen (O).

• Exist between all atoms and molecules. • Helium, and small nonpolar molecules, such as methane, CH 4(g) (in natural gas) which is why these materials are gases at room temperature

• Only forces that hold nonpolar molecules to one another

• Present in lipid bilayer

• The weakest intermolecular force.

A temporary attractive force that results when the electrons in two adjacent atoms occupy positions that make the atoms form temporary dipoles.

• Stronger than London forces
• Hold polar molecules to one anothe
• Between polar molecules, influencing protein folding

The attraction between the partially negative end of one polar molecule and the partially positive end of a different polar molecule.