Which means it's no longer carbon because carbon atoms always have six protons. So when carbon-14 decays, it goes from having six protons and eight neutrons to having seven of each. If a neutron spits out an electron and another tiny bit of mass (in the form of an exotic sounding anti-neutrino), it becomes a slimmer, more positive version of itself - a proton. The only difference between a proton and a neutron is the positive charge and a bit of mass. Instead of ejecting a neutron from its nucleus, radioactive decay in carbon-14 involves converting one of the eight neutrons into a proton. If an excess neutron is making carbon-14 unstable you'd think the obvious thing to do would be to spit out a neutron, but the maths of stability says otherwise. The different versions of carbon (or of any element) are called isotopes, and carbon-14 is the only radioactive isotope of carbon. But one in every trillion carbon atoms has got eight neutrons (carbon-14), and that's one too many neutrons as far as nuclear stability goes. About one per cent of carbon atoms have got a seventh neutron (carbon-13), so they're a bit heavier than your average carbon, but they're still stable. And 99 per cent of them have got six neutrons as well, holding those six protons together - that form of carbon, carbon-12, is stable. (The 14 in the name denotes the total number of protons and neutrons).Īll carbon atoms have got six protons - that's what makes them carbon. It's radioactive because it's got too many neutrons for its six protons, making it unstable.

The technical term is undergoing radioactive decay, and all atoms with unstable nuclei are radioactive.Ĭarbon-14 is the radioactive form of carbon, famous for its role in working out the ages of fossils.

And in the case of an atom with an unstable nucleus, that means spitting out some energy in the form of gamma radiation or high-speed particles. They do whatever it takes to get more stable. As long as there are enough attractive neutrons to keep the repulsive protons away from each other, the atomic nucleus stays in one piece.īut if the ratio of neutrons to protons is too out of whack, the nucleus is unstable, and if there's one thing physics tells us it's that unstable things don't last. Neutrons owe their 'gluing' power to a little thing called the nuclear force, which makes neutrons attractive to other neutrons and to protons. It's the neutrons that hold atomic nuclei together and stop the whole thing from flying apart. The nucleus of an atom is just a bunch of protons and neutrons jammed together, which is no mean feat because protons are positively charged, so they repel one another. The periodic table: location, location, location, Science Online,.

Carbon 14 protons