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( Carbon group)
The carbon group is group 14 (IUPAC style) in the periodic table. Once also known as the tetrels (from Latin tetra, four), stemming from the earlier naming convention of this group as Group IVA. The group consists of carbon (C), silicon (Si), germanium (Ge), tin (Sn), lead (Pb), and ununquadium (Uuq). Each of the elements in this group has 4 electrons in its outer energy level. The last orbital of all these elements is the p2 orbital. In most cases, the elements share their electrons. The tendency to lose electrons increases as the size of the atom increases, as it does with increasing atomic number. Carbon alone forms negative ions, in the form of carbide (C4-) ions. Silicon and germanium, both metalloids, each can form +4 ions. Tin and lead both are metals while unquadium is a synthetic shortlived radioactive metal. Except for germanium, all of these elements are familiar in daily life either as the pure element or in the form of compounds. However, except for silicon, none of these elements are particularly plentiful in the Earth’s crust. Carbon forms an almost infinite variety of compounds, in both the plant and animal kingdoms. Silicon and silicate minerals are fundamental components of the Earth’s crust; silica (silicon dioxide) is sand. Tin and lead, although with very low abundances in the crust, are nevertheless common in everyday life. They occur in highly concentrated mineral deposits, can be obtained easily in the metallic state from those minerals, and are useful as metals and as alloys in many applications. Germanium, on the other hand, forms few characteristic minerals and is most commonly found only in small concentrations in association with the mineral zinc blende and in coals. Although germanium is indeed one of the rarer elements, it assumed importance upon recognition of its properties as a semiconductor. Germanium is one of three elements the existence of which was predicted in 1871 by the Russian chemist Dmitry Mendeleyev when he first devised his periodic table. Not until 1886, however, was germanium identified as one of the elements in a newly found mineral.
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