Question

Why is lone pair of electrons more diffuse, and more stereo chemically active, than a bonding pair of electrons?

Answer 1

Chemical elements contain electrons, the elements are the purest form of atoms. Atoms bonded with each other to form a molecule. But all the electrons from all the atoms will not be involved in bonding and exist as lone pairs of electrons, as lone pairs of electrons occupy more space and diffuse around the central atom.

Complete answer:
Chemical elements are the purest form of atoms, the number of electrons present in atoms were responsible for the bond formation in a molecule. The total number of atoms were responsible for the bonding and non-bonding electrons. Not all the electrons from all the atoms in a molecule are involved in bond formation. Some electrons will exist as non-bonding electrons and can be known as lone pairs.
Lone pairs are the electrons that can be present on atoms as freely, and occupy more space. These are present on only one atom which contains a positively charged nucleus. Whereas bonding pairs of electrons are present between two atoms which contain positively charged nuclei.
Thus, due to the less stereochemical activity and occupancy of more space. lone pair of electrons more diffuse, and more stereo chemically active, than a bonding pair of electrons

Note:
In the water molecule, there are four bonding pairs of electrons, and two lone pairs of electrons. As lone pairs of electrons present on oxygen atoms, they are more free than the bonding pair of electrons present between oxygen and hydrogen atoms which proves the stereochemical activity of lone pairs of electrons.