Intro: We know that the atoms of the same or different elements combine together to form molecules. In a molecule, atoms are attached to each other by an attractive force which is called a chemical bond.
Kossel-Lewis approach to chemical bonding: In 1916, Kossel and Lewis provided some logical explanation of valence based on inertness of noble gases.
Electronic theory of chemical combination(Octet Rule): In 1916, Kossel and Lewis presented a theory of chemical combination which was named as electronic theory of chemical combination or octet rule. The statement of this rule is as follows:
Atoms combine by gaining or losing valence electrons from one atom to another or sharing the valence electrons to complete their octets in their valence shells.
Hydrogen Bond: A Hydrogen bond is formed when a Hydrogen atom makes a bond with a very strong electronegative atom like Chlorine, Iodin, Bromin etc.
Ex: HCl, HBr etc