The force of gravitation between the charged particle is the force which is being ignored by the scientist while studying the atom as it is very small in comparison to other forces in the atom
Explanation:
The gravitation force between the atoms are very small or you can say it is negligible to be taken into consideration, as the values as small as these procure errors and difficulties in calculation or derivation, therefore are being ignored by the scientist.
The gravitational force between the charged particles are extremely small due to the fact that it depends upon the masses of the object and masses of charged particles in the atom are small and so force is small too.