Answer:
Electron
Explanation:
According to the Bohr model, an atom contains three sub-atomic particles. These particles are electrons, protons and neutrons. Electrons are negatively charged, protons are positively charged and neutrons are neutral particles. Protons and neutrons are present in the nucleus. They are called nucleons. Electrons are present outside the nucleus.
Most of an atom's mass is in the nucleus because the atomic mass of the proton is 1.0073 AU, the atomic mass of the neutron is 1.0078 AU. The atomic mass of the electron is 0.00054858 AU.
Thus, the sub-atomic particle the electron has least atomic mass.
