Introduction
In this hypothetical atom, a negatively charged particle having a charge of magnitude 3e and mass 3m revolves around a proton. Let's discuss the behavior of this system.

Charge of the particles
The negatively charged particle has a charge of magnitude 3e, where e is the fundamental charge of an electron. The proton has a charge of magnitude e, which is opposite in sign to the charge of the negatively charged particle.

Mass of the particles
The negatively charged particle has a mass of 3m, which is three times the mass of an electron. The proton has a mass of approximately 1 atomic mass unit.

Electrostatic forces
The negatively charged particle and the proton are attracted to each other due to their opposite charges. The electrostatic force between them is given by Coulomb's law, which states that the force is proportional to the product of the charges and inversely proportional to the distance between them.

Motion of the particles
The negatively charged particle revolves around the proton in a circular path. This circular motion is due to the electrostatic force, which acts as a centripetal force, keeping the negatively charged particle in its circular path.

Effect of mass and charge on the motion
The mass of the negatively charged particle affects the speed of its motion. A particle with a larger mass requires a larger centripetal force to maintain its circular motion. The charge of the particle affects the strength of the electrostatic force and, therefore, the magnitude of the centripetal force.

Conclusion
In this hypothetical atom, a negatively charged particle having a charge of magnitude 3e and mass 3m revolves around a proton due to the electrostatic force between them. The mass and charge of the particles affect the motion of the negatively charged particle.