How compounds are formed ?
Compounds are formed by the reaction of two or more elements combined in a fixed ratio of atoms.
Let us consider the formation of HCl to understand this concept better. The chemical equation involved in the reaction is:
H2 + Cl2→2HCl
In this reaction, the bond between H-H and Cl-Cl molecule break to form atoms of H and Cl. After breaking of bond, H and Cl atom so formed combine together to give HCl. So compounds are formed by breaking of some bonds and formation of new bonds.