A lone pair, also known as an unpaired electron pair, is a set of two or more paired electrons that does not form part of any chemical bond with another atom within a molecule. These electron pairs are found on individual atoms rather than between them.

Lone pairs can be either bonding or non-bonding depending on the context:

1. Bonding lone pairs: In some cases, lone pair electrons may participate in weak intermolecular forces like hydrogen bonds instead of being strictly 'free' within an atom's valence shell but still remain associated with that particular molecule.

2. Nonbonded (or unbonded) or nonpolarized electron pairs are considered when discussing VSEPR theory as they do not contribute towards the overall shape determination for molecules according to this model since there is no repulsion exerted by other atoms due to lack of electrons sharing between them which leads us back into our definition where these types represent 'lone' entities within a molecule.

To identify lone pairs in a Lewis structure, look for dots or dashes that are not connected to another atom. These unpaired electron pairs indicate the presence of lone pairs on an individual atom.

Electron region geometry chart