Water can form hydrogen bonds with which type of substances?

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Hydrogen bonding relies on water’s polarity: the molecule has a partial positive charge on its hydrogens and a partial negative charge on the oxygen, creating sites where hydrogen bonds can form with electronegative atoms that carry lone pairs. This capability is most pronounced with other polar molecules, which have dipoles and atoms like oxygen, nitrogen, or fluorine that can accept or donate hydrogen bonds. When a polar molecule has a hydrogen attached to such an electronegative atom (for example an -O-H or -N-H group) or presents lone-pair-accepting atoms, water can align its hydrogen with a lone pair to create a hydrogen bond, enabling strong interactions and good miscibility.

Ionic lattices are held together mainly by ionic bonds; water can surround and interact with ions (hydration) via ion-dipole interactions, but that’s not hydrogen bonding in the strict sense. Nonpolar molecules lack significant partial charges and don’t offer the sites needed for hydrogen bonds. Metals have no suitable lone-pair–bearing atoms for hydrogen bonding either. Thus, water forms hydrogen bonds best with polar molecules.