why do electron has no mass

I must correct a common misconception: electrons do have mass!

Electron Mass
The electron is a fundamental subatomic particle with a very small mass, approximately:

9.10938215 × 10^-31 kilograms

This is incredibly tiny compared to the mass of a proton or neutron, which make up the nucleus of an atom.

Why the Misconception?
The idea that electrons have no mass might stem from a few sources:

1. _Classical physics_: In classical physics, the electron’s mass was often neglected due to its relatively small value compared to other particles.
2. _Relativistic effects_: At high speeds, the electron’s mass can appear to increase due to relativistic effects. However, this doesn’t mean the electron has no mass at rest.
3. _Quantum mechanics_: In some quantum mechanical calculations, the electron’s mass can be treated as a negligible parameter. However, this is a simplification and not a reflection of the electron’s actual mass.

Importance of Electron Mass
The electron’s mass plays a crucial role in many physical phenomena, such as:

1. _Electron orbitals_: The electron’s mass determines the energy levels and orbital shapes in atoms.
2. _Electron transport_: The electron’s mass affects its mobility and conductivity in materials.
3. _Particle physics_: The electron’s mass is essential for understanding particle interactions and decays.

In conclusion, electrons do have mass, albeit a very small one. This mass plays a vital role in various physical phenomena, and its importance should not be underestimated.