Facts Stated by Kossel in RELATION to Chemical Bonding

— In the PERIODIC table, the highly electronegative halogens and the highly electro-positive alkali metals are separated by noble gases.

— Formation of an anion and cation by the halogens and alkali metals are formed by gain of electron and LOSS of electron respectively.

— Both the negative and positive ions acquire the noble gas configuration.

— The negative and positive ions are stabilized by electrostatic attraction Example,

• Modes of Chemical Combination

— By the TRANSFER of electrons: The chemical bond which formed by the COMPLETE transfer of one or more electrons from one atom to another is termed as electrovalent bond or ionic bond.

— By sharing of electrons: The bond which is formed by the equal sharing of electrons between one or two atoms is called covalent bond. In these bonds electrons are contributed by both.

— Co-ordinate bond: When the electrons are contributed by one atom and shared by both, the bond is formed and it is known as dative bond or co-ordinate bond.