This was finally demonstrated in 2003, when researchers at the Institut dAstrophysique Spatiale in Orsay, France, measured the alpha emission half-life of 209Bi to be 2.01×1019 years (3 Bq/Mg), over a billion times longer than the current estimated age of the universe. Owing to its extraordinarily long half-life, for all presently known medical and industrial applications, bismuth can be treated as if it is stable and nonradioactive. The radioactivity is of academic interest because bismuth is one of a few elements whose radioactivity was suspected and theoretically predicted before being detected in the laboratory. Bismuth has the longest known alpha decay half-life, although tellurium-128 has a double beta decay half-life of over 2.2×1024 years. Bismuths extremely long half-life means that less than approximately one-billionth of the bismuth present at the formation of the planet Earth would have decayed into thallium since then. Several isotopes of bismuth with short half-lives occur within the radioactive disintegration chains of actinium, radium, and thorium, and more have been synthesized experimentally. Bismuth-213 is also found on the decay chain of neptunium-237 and uranium-233.Commercially, the radioactive isotope bismuth-213 can be produced by bombarding radium with bremsstrahlung photons from a linear particle accelerator. In 1997, an antibody conjugate with bismuth-213, which has a 45-minute half-life and decays with the emission of an alpha particle, was used to treat patients with leukemia. This isotope has also been tried in cancer treatment, for example, in the targeted alpha therapy (TAT) program. Chemical compounds
Bismuth forms trivalent and pentavalent compounds, the trivalent ones being more common.
In oxidation state +3, bismuth forms trihalides with all of the halogens: BiF3, BiCl3, BiBr3, and BiI3. All of these except BiF3 are hydrolyzed by water.Bismuth(III) chloride reacts with hydrogen chloride in ether solution to produce the acid HBiCl4.The oxidation state +5 is less frequently encountered. One such compound is BiF5, a powerful oxidizing and fluorinating agent. It is also a strong fluoride acceptor, reacting with xenon tetrafluoride to form the XeF+3 cation:
BiF5 + XeF4 → XeF+3BiF−6

Aqueous species
In aqueous solution, the Bi3+ ion is solvated to form the aqua ion Bi(H2O)3+8 in strongly acidic conditions. At pH > 0 polynuclear species exist, the most important of which is believed to be the octahedral complex [Bi6O4(OH)4]6+. Occurrence and production
In the Earths crust, bismuth is about twice as abundant as gold. The most important ores of bismuth are bismuthinite and bismite. Native bismuth is known from Australia, Bolivia, and China. The difference between mining and refining production reflects bismuths status as a byproduct of extraction of other metals such as lead, copper, tin, molybdenum and tungsten. World bismuth production from refineries is a more complete and reliable statistic.Bismuth travels in crude lead bullion (which can contain up to 10% bismuth) through several stages of refining, until it is removed by the Kroll-Betterton process which separates the impurities as slag, or the electrolytic Betts process. Bismuth will behave similarly with another of its major metals, copper. The raw bismuth metal from both processes contains still considerable amounts of other metals, foremost lead.