Polonium in the Earth's crust are not harmful. Polonium has been found in tobacco smoke from tobacco leaves grown with phosphate fertilizers. Because it is present in small concentrations, isolation of polonium from natural sources is a tedious process. The largest batch of the element ever extracted, performed in the first half of the 20th century, contained only (9 mg) of polonium-210 and was obtained by processing 37 tonnes of residues from radium production. Polonium is now usually obtained by irradiating bismuth with high-energy neutrons or protons. In 1934, an experiment showed that when natural Bi is bombarded with neutrons, Bi
Polonium tetrachloride Polonium tetrachloride Polonium tetrachloride (also known as polonium(IV) chloride) is a chemical compound with the formula PoCl. It is a hygroscopic bright yellow crystalline solid at room temperature. Above 200 °C, it tends to decompose into polonium dichloride and excess chlorine, similar to selenium tetrachloride and tellurium tetrachloride. Polonium tetrachloride is either monoclinic or triclinic. Polonium tetrachloride is bright yellow at room temperature. At its melting point (300 °C), it becomes straw yellow, and at its boiling point (390 °C), it becomes scarlet. Its vapours are purple-brown until 500 °C, when they turn blue-green. Polonium tetrachloride may be prepared by: