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Group 5 (by IUPAC style) is a group of elements in the periodic table. Group 5 contains vanadium (V), niobium (Nb), tantalum (Ta) and dubnium (Db). This group lies in the d-block of the periodic table. The group itself has not acquired a trivial name; it belongs to the broader grouping of the transition metals. The lighter three Group 5 elements occur naturally and share similar properties; all three are hard refractory metals under standard conditions. The fourth element, dubnium, has been synthesized in laboratories, but it has not been found occurring in nature, with half-life of the most stable isotope, dubnium-268, being only 29 hours, and other isotopes even more radioactive. To date, no experiments in a supercollider have been conducted to synthesize the next member of the group, either unpentpentium (Upp) or unpentseptium (Ups). As unpentpentium and unpentseptium are both late period 8 elements it is unlikely that these elements will be synthesized in the near future. ==Chemistry== Like other groups, the members of this family show patterns in its electron configuration, especially the outermost shells, though niobium curiously does not follow the trend: Most of the chemistry has been observed only for the first three members of the group, the chemistry of dubnium is not very established and therefore the rest of the section deals only with vanadium, niobium, and tantalum. All the elements of the group are reactive metals with a high melting points (1910 °C, 2477 °C, 3017 °C). The reactivity is not always obvious due to the rapid formation of a stable oxide layer, which prevents further reactions, similarly to trends in Group 3 or Group 4. The metals form different oxides: vanadium forms vanadium(II) oxide, vanadium(III) oxide, vanadium(IV) oxide and vanadium(V) oxide, niobium forms niobium(II) oxide, niobium(IV) oxide and niobium(V) oxide, but out of tantalum oxides only tantalum(V) oxide is characterized. Metal(V) oxides are generally nonreactive and act like acids rather than bases, but the lower oxides are less stable. They, however, have some unusual properties for oxides, such as high electric conductivity. All three elements form various inorganic compounds, generally in the oxidation state of +5. Lower oxidation states are also known, but they are less stable, decreasing in stability with atomic mass increase. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「group 5 element」の詳細全文を読む スポンサード リンク
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