Final answer:
Hydrogen bonding is an intermolecular force that occurs between molecules with a hydrogen atom bonded to highly electronegative atoms like N, O, or F, and varies in strength. While much weaker than covalent bonds, hydrogen bonds are stronger than other van der Waals forces and affect physical properties and bond stretch frequencies.
Step-by-step explanation:
A hydrogen bond is an intermolecular attractive force that occurs between certain molecules. These bonds involve a hydrogen atom that is covalently bonded to a small, highly electronegative atom like nitrogen (N), oxygen (O), or fluorine (F), which in turn is attracted to an unshared pair of electrons on a neighboring molecule.
The strength of hydrogen bonds varies between molecules due to factors such as the electronegativity of the atoms involved and the presence of lone pairs of electrons that can participate in bonding.
The strength of a typical hydrogen bond is about 5 to 10% of that of a covalent bond. This makes it much weaker than covalent bonds but still generally stronger than other types of dipole-dipole attractions and London dispersion forces.
Molecules without highly electronegative atoms or available hydrogen atoms do not form hydrogen bonds, leading to different bond lengths and stretch frequencies in molecular spectra.
Additionally, intermolecular forces like hydrogen bonds influence the physical properties of substances, such as boiling points and surface tension.
Temperature also affects intermolecular forces; higher temperatures increase kinetic energies, which can overcome intermolecular forces, leading to a state change from solid to liquid or liquid to gas.