Which fundamental force is responsible for holding nucleons in the nucleus of an atom together?

The strong nuclear force is the fundamental force responsible for holding nucleons—protons and neutrons—in the nucleus of an atom together. This force operates at very short ranges, typically on the order of a few femtometers (10^-15 meters), which is roughly the size of atomic nuclei. The strong nuclear force is significantly stronger than both the electromagnetic and gravitational forces, but its effectiveness diminishes quickly with distance.

Within the nucleus, protons, which carry a positive charge, would naturally repel each other due to the electromagnetic force. However, the strong nuclear force overcomes this repulsion by binding the protons and neutrons together, ensuring the stability of the nucleus. This binding occurs through the exchange of particles called gluons, which mediate the strong interaction between quarks, the fundamental constituents of protons and neutrons.

In contrast, the gravitational force is much weaker than the strong nuclear force and is not significant at the scale of individual nucleons. The electromagnetic force also does not play a role in holding nucleons together due to the repulsive nature of like charges; hence, neither of these forces can effectively hold the nucleus intact. The weak nuclear force is responsible primarily for processes like beta decay, not for binding nucleons