Electron rich hydrides have excess electrons that are present as lone pair. A pair of electrons occupying an orbital in an atom or molecule and not directly involved in bonding is called a lone pair of that atoms.
For example, Nitrogen has 5 electrons in its valence shell. Therefore its valency is 3. Nitrogen forms a covalent bond which is formed by sharing of electrons. It will share 3 electrons with another atom, and 2 electrons will remain in its valence shell. The remaining 2 electrons are its lone pair.
- A lone pair is an electron pair in the outermost shell of an atom that is not shared or bonded to another atom. It is also called a non-bonding pair.
- To identify lone pairs in a molecule, figure out the number of valence electrons of the atom and subtract the number of electrons that have participated in the bonding.
- A lone pair is created due to the absence of empty orbitals.