What makes up the nucleus of an atom?

The nucleus of an atom is made up of protons and neutrons, collectively known as nucleons.

The nucleus is the very small, extremely dense central region of an atom. It is composed of two types of subatomic particles: protons and neutrons. These particles are collectively referred to as nucleons because they reside in the nucleus. Protons carry a positive electrical charge, while neutrons have no electrical charge, they are neutral.

The number of protons in the nucleus, also known as the atomic number, determines the identity of an atom. For example, an atom with one proton is hydrogen, an atom with two protons is helium, and so on. The number of neutrons can vary, leading to different isotopes of the same element. For instance, carbon-12 and carbon-14 are both forms of carbon, but they have different numbers of neutrons.

The nucleus is held together by the strong nuclear force, one of the four fundamental forces of nature. This force is much stronger than the electromagnetic force, which would otherwise cause the positively charged protons to repel each other. However, the strong nuclear force only works over very short distances, roughly the size of the nucleus itself.

Despite its tiny size, the nucleus contains almost all of an atom's mass. This is because protons and neutrons are much heavier than electrons, the other major component of an atom. However, the nucleus is only a tiny fraction of the atom's total size. Most of an atom is actually empty space, with the electrons orbiting far from the nucleus.

In summary, the nucleus is a tiny, dense core at the heart of an atom, composed of protons and neutrons. It determines the identity of the atom and contains almost all of its mass.