What is hydrogen bonding? How can you tell whether a compound has hydrogen bonding?

Intermolecular forces are the forces of attraction or repulsion between neighboring particles (atoms, molecules, or ions). These forces are crucial because they determine the physical properties of substances like boiling and melting points, viscosity, and solubility. Among the various types of intermolecular forces, hydrogen bonds are among the strongest.

Aside from hydrogen bonding, there are other types of intermolecular forces. Van der Waals forces are the weakest, including London dispersion forces which occur in all molecules, whether polar or nonpolar. Dipole-dipole attractions are stronger than London forces and occur between polar molecules. A special case of these are ion-dipole interactions, important in solutions of ions. Hydrogen bonds can be viewed as an extremely strong form of dipole-dipole interaction but only occur when hydrogen is bound to a highly electronegative atom.

Electronegativity is a measure of an atom's ability to attract and hold onto electrons within a chemical bond. The Pauling scale is commonly used to measure electronegativity, with fluorine being the most electronegative element. Understanding electronegativity is key to predicting the type and strength of chemical bonding a molecule can exhibit, including hydrogen bonding.

The difference in electronegativity between atoms in a molecule contributes to the polarity of the molecule. When the difference is large, the bond is considered ionic, with one atom effectively 'donating' its electron to the other. As the difference becomes smaller, the bond is increasingly seen as covalent, where electrons are more equally shared. But, when hydrogen is covalently bonded to an atom with high electronegativity, like nitrogen, oxygen, or fluorine, this creates a large enough dipole for hydrogen bonding to occur.

Chemical bonding is the process of attraction that holds atoms together to form substances with distinct properties. There are three primary types of chemical bonds: Ionic, covalent, and metallic. Ionic bonds form between metals and nonmetals with a significant difference in electronegativity, resulting in the transfer of electrons. Covalent bonds, on the other hand, involve the sharing of electrons and typically occur between two nonmetals.

Metallic bonding is found in metal elements, where electrons are free to move around, giving rise to properties like conductivity. Hydrogen bonding is often taught as a type of chemical bonding, but it is technically an intermolecular force. However, it is stronger than most other intermolecular forces and has a significant impact on the properties of the substances it occurs in, such as water's high boiling point relative to its molecular mass.