H Chem - Intermolecular Forces and Properties

Front

What are van der Waals forces?

Back

Intermolecular forces acting between molecules, including London dispersion forces and permanent dipole-permanent dipole interactions, and Hydrogen bonding

Front

What are London dispersion forces?

Back

Forces of attraction that can operate between all atoms and molecules, they arise due to the random movement of electrons which creates a temporary dipoles which then induces a dipole in a neighbouring atom or molecule.

Front

How is the strength of London dispersion forces determined?

Back

It is related to the number of electrons within an atom or molecule.

Front

What defines a polar molecule?

Back

A molecule with a permanent dipole.

Front

What are permanent dipole-permanent dipole interactions?

Back

Additional electrostatic forces of attraction between polar molecules, stronger than London dispersion forces for molecules with similar numbers of electrons.

Front

What is a hydrogen bond?

Back

An electrostatic force of attraction between molecules containing highly polar bonds, such as those with hydrogen bonded to fluorine, oxygen, or nitrogen.

Front

How do hydrogen bonds compare in strength to other bonds?

Back

Stronger than other forms of permanent dipole-permanent dipole interaction but weaker than a covalent bond.

Front

What properties can be rationalized by intermolecular forces?

Back

Melting points, boiling points, and viscosity.

Front

How do the melting and boiling points of polar substances compare to non-polar substances?

Back

Polar substances have higher melting and boiling points than non-polar substances with similar numbers of electrons.

Front

What properties are affected by hydrogen bonding?

Back

Boiling points, melting points, viscosity, and solubility/miscibility in water.