CBSE Class 11-science Answered
Let me take an example to explain it in a simple way. Two atoms H and Cl are not stable as individual atoms. SO, they combine with each other chemically. Now, this product formed by chemical combination of H and Cl is a molecule HCl. The properties of a molecule HCl are very different from atoms H and Cl.
Now, you need to understand that a molecule is a microscopic species. When we talk of substances we cannot say atoms or molecules. So, we say a compound. a compound of HCl is a pure substance which will have many molecules of HCl taken together. These molecules are bonded to each other through some forces called intermolecular forces which you will study in Class XI.It will have all the properties of a molecule.
In a similar way when you say, an atom and an element. An element is many atoms taken together of the same atom. Element sodium is a pure substance which comprises of many sodium atoms.
A compound is a pure substance consisting of similar type of molecules which are made of either same (H2) or different elements (H2O).
A molecule is smallest part of a compound which is formed by chemical reaction of a group of atoms. For example: a water molecule is formed by combining two hydrogen atoms and one oxygen atom.
All compounds are molecules, but all molecules are not compounds.