Sunday, June 7, 2009

Isotopes

First off all, the incredibly useful complete table of nuclides.

Second, some of the stranger isotopes of hydrogen. Deuterium, 2H, has a neutron in the nucleus. It is stable and forms heavy water, D2O. Bacteria can grow in heavy water, but mammals become sterile at 25% replacement and die at 50% replacement of regular water due to different cellular effects. It's 11% more dense than regular water and is used as a moderator in some nuclear reactors.
Tritium, 3H, is radioactive with a 12-year half life. It's used in self-powered lighting application.
Hydrogen-4 thru Hydrogen-7 are all artificially synthesized and have half-lives in the 10-22 second range.

Third, strange Helium isotopes. The diproton is a nucleus with just two protons and no neutrons.
Isotopes with up to 8 neutrons have been prepared.

Fourth, neutrons have three main isotopes. Single neutrons are unstable and decay into a single proton and electron and antineutrino - beta decay. Dineutronium and tetraneutronium are theoretical and have not been synthesized. The former should be fairly stable; the latter will not.

Finally, see exotic atoms.

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