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

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.

i just did an experiment like this in my science class. also the answer is yes, it will get separated because they are two opposites meaning if they are opposite they can not attract.

hope this .!