Definition of Molecule | Define molecule in chemistry

Here in this topic we will discuss definition of molecule in chemistry, molecule examples and properties of molecules.

                “Smallest particle of elements or compounds which may survive solely is called Molecule.”

Composition & Molecule example:

                It consist of,

1. One atom of the element (monoatomic molecule) E.G., He, Ne, Xe etc.
2. Two atoms of the same element (mononuclear diatomic molecule) e.g., H₂, O₂, N₂ etc.
3. Two atoms of different elements (heteronuclear diatomic molecule) e.g., CO, HCl, HBr etc.
4. Many atoms of the same o different e.g., S₈, C₆H₆, C₆H₁₂O₆ etc.

Important Properties of Molecules:

1. Molecules of same substance are similar in all aspects.
2. Molecules have empty spaces in between them which are minimum in solids and maximum in gases.
3. Molecules have ceaseless motions. i.e., Molecules of gases vibrate, rotate and move from one place to another inside the container or available space, whereas molecules of liquids move below the surface of liquid. However, molecules of solids vibrate only.
4. Molecules attract each other.
5. Molecules possess definite quantity of kinetic and potential energy.
6. Molecule of reacting substances collide with each other. Whenever the energy of colliding molecules becomes equal to Activation Energy (E_a) or greater than this, they form activated complex, which convert into the molecule of the product.