Final answer:
Intermolecular forces are the electrostatic interactions between molecules, significantly weaker than covalent or ionic bonds within molecules, but essential for the formation of liquids and solids from gases. They include dipole-dipole interactions, hydrogen bonding, and London dispersion forces, and dictate many physical properties of substances.
Step-by-step explanation:
Intermolecular forces refer to the electrostatic interactions that occur between molecules. Unlike intramolecular forces, which are the forces within a molecule that hold it together, such as covalent bonds, intermolecular forces are the attractions between different molecules. These forces are crucial in determining the physical properties of substances, such as boiling and melting points, viscosity, and surface tension.
There are several types of intermolecular forces, including dipole-dipole interactions, hydrogen bonding, and London dispersion forces. Dipole-dipole interactions occur between molecules with permanent dipoles, whereas hydrogen bonding is a strong type of dipole-dipole interaction that occurs specifically between a hydrogen atom in one molecule and a highly electronegative atom (such as oxygen, nitrogen, or fluorine) in another molecule.
London dispersion forces are present in all molecules and are caused by temporary fluctuations in electron distribution within molecules, leading to temporary dipoles.
Intermolecular forces are significantly weaker than intramolecular forces but are nonetheless vital for the formation of liquids and solids from gases. They explain why, under certain conditions, gas molecules condense to form distinct phases and also account for deviations from the ideal gas law at high pressures. Essentially, intermolecular forces govern the behavior and interactions of molecules in different states of matter.