Why don't protons in a nucleus repel each other?

The atomic nucleus is the small, dense region consisting of protons and neutrons at the center of an atom.
A model of the atomic nucleus showing it as a compact bundle of the two types of nucleons:
protons (red) and neutrons (blue).
By Marekich - Own work (vector version of PNG image), CC BY-SA 3.0, Link

The atomic number Z of a chemical element is the number of protons found in the nucleus of an atom. Since neutrons are neutral while protons are positively charged with a charge that is, in absolute value, equal to the electron charge, the atomic number is identical to the charge number of the nucleus. In an uncharged atom, the atomic number is also equal to the number of electrons, and that is why the atomic number uniquely identifies a chemical element. For instance, Z=1 is called hydrogen and Z=6 carbon.

The world nuclide is referred to a 'species of nucleus', characterized by its number of protons Z, its number of neutrons N, and its nuclear energy state. Identical nuclei belong to one nuclide, for example each nucleus of the carbon-13 nuclide is composed of 6 protons and 7 neutrons. On the other hand, the members of the group of all the nuclides of the same elements are called isotopes. That is, the nuclides with equal atomic number, i.e., of the same chemical element but different neutron numbers, are called isotopes of that element.

Stable nuclides are nuclides that are not radioactive and so (unlike radionuclides) do not spontaneously undergo radioactive decay. It has been found that there are 80 elements with one or more stable isotope. For instance, carbon has 15 known isotopes, from carbon-8 to carbon-22, of which carbon-12 and carbon-13 are stable.

But, because of the fact all the protons have the same charge and are very closed to one another in the nucleus, one expects that they repel each other by a strong electric force, a force that must be much stronger than the force acting between the nucleus and the surrounding electrons. This force should make the nucleus explode. Therefore, no nuclide with more than one proton should be stable, that is, the only stable element should be hydrogen!

Please, explain your reasoning. You can post your attempted answers in the comment box below. Please, do not use Facebook or Twitter to give your answers. 


  1. Strong nuclear force within nucleus overcomes the electromagnetic force. Simples.

    1. Good! Protons do repel each others in the nucleus due to the positive electric charges they posses, but they also interact by the strong nuclear force, which is an atractive proton-proton, proton-neutron and neutron-neutron force that keeps the nucleus together.
      This is a very useful cognitive conflict in order to introduce students to the strong nuclear force in freshman (9th) grade.