Van der Waals Bonding

Secondary bonds are weak in comparison to primary bonds.

They are found in most materials, but their effects are often overshadowed by the strength of the primary bonding.

Secondary bonds are not bonds with a valence electron being shared or donated. They are usually formed when an uneven charge distribution occurs, creating what is known as a dipole (the total charge is zero, but there is slightly more positive or negative charge on one end of the atom than on the other).

These dipoles can be produced by a random fluctuation of the electrons around what is normally an electrically symmetric field in the atom.

Once a random dipole is formed in one atom, an induced dipole is formed in the adjacent atom.

This is the type of bonding present in N2 molecules, and is known as Van Der Waals Bonding.

Van der Waals

Secondary bonding may also exist when there is a permanent dipole in a molecule due to an asymmetrical arrangement of positive and negative regions.

Molecules with a permanent dipole can either induce a dipole in adjacent electrically symmetric molecules, and thus form a weak bond, or they can form bonds with other permanent dipole molecules.