Difference Between Atom and Molecule

What is Atom?

Atoms are the constituent elements of matter and the definition structure of elements. The term “atom” comes from the Greek word indivisible, because in the past atoms were thought to be the smallest things in the universe.

The structure of an atom is a core made up of protons and neutrons around which electrons gravitate.

Atoms are incredibly small; in fact, they are the smallest things that we can observe with our unaided eyes. Even though they are so small, atoms are extremely important. They are the building blocks of everything in the universe, from the smallest pieces of dust to the largest planets.

Atoms are held together by forces that are much stronger than the forces that hold us together. The nucleus of an atom is held together by the strong nuclear force, while the electrons that orbit the nucleus are held together by the electromagnetic force.

The electrons in an atom are attracted to the nucleus by the electrostatic force. This force is created by the electric charges of the particles.

The electromagnetic force between the nucleus and the electrons is what keeps the nucleus from flying apart.

What is Molecule?

A molecule is the smallest particle of an element or compound that possesses the chemical characteristics of that element or compound. Molecules are composed of atoms, which are the foundation units of matter. The term “molecule” was first used by a Scottish chemist, Daniel Rutherford, in 1784.

Molecules are held together by forces that are either electromagnetic or Van der Waals forces. The types of molecules range from the very simple, such as oxygen (O2), to the very complex, such as proteins and DNA.

The study of molecules is called molecular biology. Molecules can be organic or inorganic, polar or non-polar. The size of a molecule is typically measured in nanometres (nm).

Molecules can be either simple or complex. Simple molecules are made up of only a few atoms, while complex molecules are made up of many atoms.

Difference between Atom and Molecule

  • Atoms are the fundamental units of matter and the definitional structure of elements. The molecules are clusters of atoms held together by chemical bonds.
  1. The term “atom” is a Greek word for indivisible, atoms are the tiniest things in the universe and could not be split. Molecules have chemical bond, these bonds can be covalent, ionic, or hydrogen bond.
  • The structure of an atom is a core made up of protons and neutrons around which electrons gravitate. Molecules can be simple, such as water (H2O), or complex, such as DNA. The structure of a molecule determines its operation.
  • Unlike atoms, molecules can be divided into smaller pieces.

Comparison Table Between Atom and Molecule

Comparison of ParametersAtomMolecule
Chemical NatureA group of atomsIndividual chemical species
symbolA chemical formula shows the symbol of atoms present in the molecule.An English letter denotes the symbol of a chemical component to which the atom belongs.
ExistenceStableIndividual atoms are unstable
MassThe mass of a molecule is given by molecular mass.Standard atomic weight gives the mass of an atom.
SizeLarge compared to a single atom.The smallest constituent of matter.


  1. www.ub.edu/hcub/hfq/sites/default/files/Thomson_model%286%29.pdf
  2. https://www.annualreviews.org/doi/abs/10.1146/annurev.neuro.20.1.567