Loan pair electrons or non-bonding electrons are valence electrons that are not involved in covalent bonding. They are found in pairs and are typically located in the outermost shell of an atom.

Examples of molecules or ions with lone pair electrons include:

- Water (H2O): each oxygen atom has two lone pairs of electrons

- Ammonia (NH3): the nitrogen atom has one lone pair of electrons

- Carbon dioxide (CO2): each oxygen atom has two lone pairs of electrons

Lone pairs of electrons can play an important role in the properties and reactivity of molecules. For example, they can be involved in hydrogen bonding, which is a type of non-covalent interaction between a hydrogen atom and an electronegative atom (such as nitrogen, oxygen, or fluorine). Lone pairs of electrons can also make molecules more reactive by providing a site for nucleophilic attack.