An atom is held together by three forces: the strong nuclear force, the electromagnetic force, and the weak nuclear force.
The strong nuclear force is the strongest of the three forces and is responsible for binding the protons and neutrons together in the nucleus of an atom. The strong nuclear force is a short-range force that acts only over a very small distance, and it is strong enough to overcome the repulsive forces between the protons, which are positively charged particles.
The electromagnetic force is the second strongest of the three forces, and it is responsible for binding the electrons to the nucleus of an atom. The electromagnetic force is a long-range force that acts over a larger distance than the strong nuclear force, and it is caused by the attraction between opposite charges (positive and negative).
The weak nuclear force is the weakest of the three forces, and it is responsible for certain types of radioactive decay, such as beta decay. The weak nuclear force is a short-range force that acts only over a very small distance, and it is much weaker than the strong nuclear force and the electromagnetic force.
Overall, the three forces at work that hold an atom together are the strong nuclear force, the electromagnetic force, and the weak nuclear force. These forces act at different ranges and with different strengths, but they all play a crucial role in maintaining the stability and integrity of an atom.