There are three types of intermolecular forces: London dispersion forces (LDF), dipole- dipole interactions, and hydrogen bonding. Molecules can have any mix of these three kinds of intermolecular forces, but all substances at least have LDF.
Explanation:
London Dispersion Forces (LDFs):
LDFs exist for all substances, whether composed of polar or nonpolar molecules
LDF arise from the formation of temporary instantaneous polarities across a molecule from the circulations of electrons.
An instantaneous polarity in one molecule may induce an opposing polarity in an adjacent molecule, resulting in a series of attractive forces among neighboring molecules.
Molecules with higher molecular weights have more electrons. This makes their electron clouds more deformable from nearby charges, a characteristic called polarizability.
As a result, molecules with higher molecular weights have higher LDF and consequently have higher melting points, boiling points and enthalpies of vaporization.
Dipole-Dipole Interactions:
Dipole-dipole forces exist between molecules that are polar-those that have a permanent dipole moment due to uneven sharing of electrons
This uneven sharing gives one side of the molecule a partial positive charge (δ+) and the other side a partially negative charge (δ-)
The polarities of individual molecules ten to align by opposites, drawing molecules together and thereby favoring a condensed phase.
Substances with dipole-dipole attractions tend to have higher melting and boiling points compared to nonpolar molecules, which only have LDF.
Hydrogen Bonds:
When a hydrogen atom is covalently bonded to nitrogen, oxygen or fluorine a very strong dipole is formed.
The dipole-dipole interactions that result from these dipoles is known as hydrogen bonding.
Hydrogen bonding is an especially strong form of dipole-dipole interaction.
Answers & Comments
Answer:
There are three types of intermolecular forces: London dispersion forces (LDF), dipole- dipole interactions, and hydrogen bonding. Molecules can have any mix of these three kinds of intermolecular forces, but all substances at least have LDF.
Explanation:
London Dispersion Forces (LDFs):
Dipole-Dipole Interactions:
Hydrogen Bonds: