| Tritium | |
|---|---|
 Location of tritium in the table of nuclides | |
| General | |
| Name, symbol | tritium, triton, T, 3H |
| Isotope of | Hydrogen |
| Neutrons | 2 |
| Protons | 1 |
| Nuclide data | |
| Natural Abundance | trace |
| Half-life | 12.32 years |
| Decay mode | beta emission |
| Decay energy | 0.018590 MeV |
| Decay product(s) | 3He |
| Isotope mass | 3.0160492 u |
| Spin | ½+ |
| Excess energy | 14,949.794Âą 0.001 keV |
| Binding energy | 8,481.821Âą 0.004 keV |
| History | |
| Discoverer | Ernest Rutherford, Mark Oliphant and Paul Harteck |
| Location discovered | ? |
| Date discovered | 1934 |
Tritium (symbol T or 3H, also known as hydrogen-3) is a radioactive isotope of hydrogen. The nucleus of tritium (sometimes called a triton) contains one proton and two neutrons, whereas the nucleus of protium (by far the most abundant hydrogen isotope) contains one proton and no neutrons. Naturally occurring tritium is extremely rare on Earth, where trace amounts are formed by the interaction of the atmosphere with cosmic rays. The name of this isotope is formed from the Greek word "tritos" meaning "third".[1]
Tritium watch.
History[]
Tritium was first predicted in the late 1920s by Walter Russell, but actually produced in 1934 by Ernest Rutherford, Mark Oliphant and Paul Harteck from deuterium. Rutherford was unable to isolate the tritium, although Luis Alvarez and Robert Cornog later did. Willard F. Libby discovered that tritium could be used to date water, and therefore wine.[1]
Tritium is among the most mildly radioactive of nuclides, It decays to 3He with a total ground-state to ground state energy change of 18.6 keV. That's less than the kinetic energy of electrons in a cathode-ray television picture tube. In addition, it appears that the transition goes to 3He's ground state, so it produces no gammas[2]. Decelerating an ejected electron will produce photons, but photons energetic enough to be called x-rays are unlikely. Theoretically, ingesting tritium is hazardous - but those claims seem to be as much a matter of whining as science.
Production[]
Tritium occurs naturally, but at concentrations too low to make extracting the tritium worthwhile. It is usually made in reactors by neutron bombardment of 6Li:
6Li + n --> 7Li* --> 3H + 4He.
High-energy neutrons can produce tritium by a very similar reaction. Physicists abruptly learned this on March 1, 1954, when the Castle Bravo nuclear test yielded 2.5 times the amount of energy expected. (It also yielded at least one international incident and an enormous expense to repair damage done.)
Properties[]
Applications[]
There are a variety of uses for tritium, but the most common application is use in signs and emergency lights. Even though electrons emitted by tritum decay have very low energy by nuclear standards, they have plenty of energy to stimulate phosphors. This allows them to be used as light sources which do not depend on external power.
References[]
- â 1.0 1.1 Tritium - Wikipedia
- â NuDat database; available online, easily accessed by the search term "chart of nuclides".