Inside the nucleus of some atoms, protons appear to be doing very unexpected things. They are pairing up far more often than usual when they get extremely close to each other, and physicists don’t ...

An element's atomic number defines it. An element with 17 protons will always be chlorine. However an element's mass numbers can vary, which means that it can have different numbers of neutrons. So ...

This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American We take it for granted that there exists a ...