Bismuth compounds elemental iodine

Many elements such as tin, copper, zinc, lead, mercury, silver, platinum, antimony, arsenic, and gold, which are so essential to our needs and civilization, are among some of the rarest elements in the earth s crust. These are made available to us only by the processes of concentration in ore bodies. Some of the so-called rare-earth elements have been found to be much more plentiful than originally thought and are about as abundant as uranium, mercury, lead, or bismuth. The least abundant rare-earth or lanthanide element, thulium, is now believed to be more plentiful on earth than silver, cadmium, gold, or iodine, for example. Rubidium, the 16th most abundant element, is more plentiful than chlorine while its compounds are little known in chemistry and commerce. 

C. It occurs naturally by radioactive decay from uranium and thorium isotopes. Astatine forms at least 20 isotopes, the most stable astatine-210hasahalf-lifeof8.3 hours. It can also be produced by alpha bombardment of bismuth-200. Astatine is stated to be more metallic than iodine at least 5 oxidation states ate known in aqueous solutions. It will form interhalogen compounds, such as Atl and AtCl. The existence of At2 has not yet been established. The element was synthesized by nuclear bombardment in 1940 by D. R. Corson, K. R. Mac-Kenzie, and E. Segre at the University of California. 

In the first section of this chapter some of the properties of the elements hydrogen, carbon, nitrogen, phosphorus, arsenic, antimony, bismuth, oxygen, sulfur, selenium, tellurium, fluorine, chlorine, bromine, and iodine are described. The following sections are devoted to some of their compounds with one another, especially the single-bonded normal-valence compounds. Compounds of nonmetals with oxygen are discussed in the following chapter. 

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