Limits on Atom Weight

Atoms are made up of protons, neutrons, and electrons. Protons and neutrons are collectively called nucleons and they are found in the nucleus of an atom. The number of protons in an atom's nucleus determines what element it is, while the number of neutrons determines the isotope of that element.

As the number of protons in an atom's nucleus increases, the atom becomes heavier. However, there are limits to how many protons an atom's nucleus can hold before it becomes unstable. This is because the strong nuclear force that holds the nucleus together is only strong enough to overcome the electromagnetic repulsion between the positively charged protons up to a certain point.

The largest naturally occurring element is uranium, which has 92 protons in its nucleus. Scientists have created heavier elements in the laboratory by smashing together lighter atoms, but these elements are highly unstable and decay quickly.

Based on current understanding of nuclear physics, it is believed that the heaviest stable element that could exist is around element 126, with a nucleus containing 126 protons and a corresponding number of neutrons to keep the nucleus stable. Beyond that, the strong nuclear force is not strong enough to overcome the repulsive force between the protons, and the nucleus becomes unstable, leading to radioactive decay.