At the Heart of the Atom


What holds a nucleus together?

Protons, all being charged positively, will repel each other. So there must be an attractive force that holds the nucleus together. The strong nuclear force acts between protons and protons, protons and neutrons, and neutrons and neutrons, all with the same strength. Because the strong force acts the same on protons and neutrons, the two particles are frequently lumped together under the name nucleon. While the repulsive electromagnetic force acts over long distances, the strong nuclear force only acts between nucleons that are in contact. Nucleons have angular momentum, or spin, and the strong force depends on the relative orientation of the spins. The force is stronger if the spins are in opposite directions.


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