Metals/metalloids radioactive isotopes

Each Group VIA element is less electronegative than its neighboring halogen. Oxygen and sulfur are clearly nonmetallic, but selenium is less so. Tellurium is usually classified as a metalloid and forms metal-like crystals. Its chemistry is mostly that of a nonmetal. Polonium is a metal. All 29 isotopes of polonium are radioactive. 

Among the most observed chemical contaminants are toxic minerals (metals, metalloids and other inorganic compounds), radioactive isotopes, mycotoxins and other microbial toxins, halo-genated organic compounds, phytotoxins as representatives of natural contaminants and others. For the selection of contaminants to be covered in this chapter, a number of criteria were taken into account, the most important of which include ... 

The table "Parameters of the Diffusion of Nonmetals into Metals with the formation of Refractory Compounds" mainly gives data on the parameters of reaction diffusion, i.e., diffusion occurring with the formation of the corresponding compounds in a number of cases, however, data have been utilized on the ordinary heterodiffusion of metalloids into transition metals. The majority of the data have been obtained by the classical method, and the minority by the use of radioactive isotopes. 

Radon lies on the diagonal of the Periodic Table between the true metals and nonmetals and is classed as a metalloid. As the heaviest and most metallic of the naturally occurring noble gases, radon has the lowest ionization energy of the group (1030 kJ mol ) consequently, it is expected to be the most reactive. The chemistry of radon is, however, less extensive than the chemistries of krypton and xenon and is rendered considerably more difficult because no stable isotopes of this element exist. The inherent radiation hazard that accompanies the intense radioactivity of radon requires tracer level experimentation. Nevertheless, evidence has been obtained that radon forms a difluoride and several complex salts. 

Atomic masses are relative to carbon-12. For 12 elements, the atomic mass is given as an interval (see Section 2-5). For certain radioactive elements, the numbers listed in parentheses are the mass numbers of the most stable isotopes. Metals are shown in tan, nonmetals in blue, and metalloids in green. The noble gases (also nonmetals) are shown in pink. Just days before this text went to press, the lUPAC announced they had verified claims of the discovery of elements 113,115,117, and 118. 

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