This is a subatomic particle with a negative charge and very little mass.

Answer: Electron.

Explanation: This would be an electron, with a chare of one elementary charge negative and with a mass of 9.109x10^-31 Kg.

Electrons play an essential role in numerous physical phenomena, such as electricity, magnetism, chemistry and thermal conductivity, and are one of the fundamental particles.

This would be an electron!