Bismuth (atomic symbol Bi) is in group 15 and period 6 of the periodic table and is classified as one of the “other metals” along with aluminum, gallium, indium, tin, thallium and lead. Bismuth was actually believed to be a form of lead or possibly even tin since the fifteenth century. The French chemist Claude Geoffroy the Younger identified it officially as a separate element in 1753. Bismuth is a white, crystalline metal in pure form, and its name is possibly a Latinization of the German word “weissmuth,” meaning “white mass.” It shares a unique property with only four other elements in that it is less dense as a solid than as a liquid. Bismuth, silicon, gallium, antimony and germanium all expand when they freeze, like water.
Bismuth is the most diamagnetic of all metals with the highest Hall effect, meaning it resists being magnetized, creating a magnetic field in opposition to any other magnetic field, and also exhibiting the greatest electrical resistance. It is the least conductive metal of heat with the exception of mercury, and is a poor conductor of electricity. Bismuth is very similar to the elements in the transition metals group, but is classified among the other metals because of its variable oxidation state and presence of valence electrons only in its outer shell. It is the heaviest of the other metals, the only one that is non-toxic, and it does not corrode in air. It does tarnish to iridescent pinks, yellows and blues, giving it a more crystal appearance.
Although considered to be stable, bismuth actually just has an extremely slow rate of decay. Its half-life is 1.9 x 10^19 years. The rate of decay is so slow that if a hypothetical 100 grams of bismuth existed 14 billion years ago, there would be 99.9999999 grams left today. It has 33 unstable isotopes with mass numbers between 185 and 217. Only Bi-209 was thought to be stable, but in 2002 research showed that via alpha decay it will become thallium-205.
Bismuth has a number of uses in medicine in the forms of bismuth subnitrate and subcarbonate, which treat ulcers and diarrhea. It is sometimes used for yellow pigment in cosmetics as bismuth oxychloride. It is combined with other metals to create low-melting alloys and is used in fire detection and extinguishing systems because of its melting point (520.52 degrees F). It is also used as a replacement for lead in items such as ammunition, fishing sinkers and plumbing. It is obtained commercially as a byproduct of the refining processes of copper, lead, tin, silver, gold and zinc. It is also found free in nature in minerals such as bismuthinite (Bi2S3) and bismite (Bi2O3).
