In 1916, an American chemist NEWTON LEWIS proposed that chemical bonds are formed between atoms due to the interaction of electrons between them.
What is Chemical Bonding
A Chemical Bond is a term used when two or more atoms combine to form a stable compound or molecule. The reason why atoms or elements combine lies in their electronic shell configurations. Because in a chemical bond the valance shell of one atom will have less electron and the other will have more or equal, hence they will combine together to either share or donate the electrons to each other making a complete stable electronic configuration.
For example, when a Li atom and F atom combine then, Li can achieve a complete configuration by donating an electron to Fluorine, which also achieves complete electronic configuration as shown;
Newton Lewis observed that many elements are most stable when they have complete valence shells (eight electrons). Then he came to know that atoms having less than 8 electrons in their valance shell bond together to share electrons and complete their shells. While some of the Lewis predictions prove incorrect and there are compounds which have more than 8 electrons in their valance shell and are stable. These compounds fall in the categories of exceptional compounds.
There are two types of bonding present: 1. Ionic and 2. Covalent
Ionic bond: In Ionic Bond, electrons are completely transferred from one atom to another so that the atoms achieve stable electronic configuration. In this process, formation of ions takes place .The positive charged ions get attracted to negative charged ions, which forms the basis of an IONIC BOND. For example, in the reaction of Sodium (Metal) with Chlorine (Non metal),
Ionic compounds are generally solids, results from inter molecular forces between them .The chemical bond formed between Ionic compounds are the strongest of all. Ionic bonds dissolve very easily in water and other polar solvents. Ionic bonds conduct electricity and they have very high melting and boiling points.
Covalent bond: Covalent bonds are formed between the atoms where sharing of electrons takes place. It is opposite to Ionic bonds. Covalent bonds mostly occur between Non-Metals. A good example of a covalent bond is the bond formed between two Hydrogen atoms. Covalent bonds have no charges and no ions in their compounds. These bonds are weaker in comparison to Ionic.
The Chemical Bonds are basically the result of the electrical forces of attraction acting between the atoms, resulting in the formation of molecules. Different types of Chemical Bonds present in the compounds have varying intensity which is directly responsible for the physical and chemical properties of molecules and compounds like hardness , melting , boiling , conductivity , solubility , etc.