铂

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铂(platinum)

金属化学元素，过渡元素之一，化学符号Pt，原子序数78。是一种非常重的银白色贵金属，质地软，具延展性，熔点很高（1,769℃），耐腐蚀和抗化学反应。一般加入少量的铱形成更硬、更强的合金，而又包括了铂的优点。通常铂在砂矿中以合金形式存在，其中包含80～90%的纯铂，或者不多见的是与砷或硫结合在一起。在高温实验室的工作中它有不可取代的地位，用作电极、容器以及电接触，即使在非常热的情况下仍然能抗化学作用。铂还用作补牙的合金以及外科手术用的别针。铂被称为「白金」，用作贵重的首饰，比金要贵得多。重量和长度的国际标准原型用90%的铂，10%的铱制成。76.7%铂与23.3%钴的合金是已知最强的永久磁体。铂在它的原子价里有2价或4价。这些化合物中有许多是配位错合物。铂与它的某些化合物都是有用的催化剂，尤其用於氢化作用中，以及用作催化转化剂。

English version：

platinum

Metallic chemical element, one of the transition elements, chemical symbol Pt, atomic number 78. A very heavy, silvery-white precious metal, it is soft and ductile, with a high melting point (3,216°F, or 1,769°C) and good resistance to corrosion and chemical attack. Small amounts of iridium are commonly added for a harder, stronger alloy that retains platinum's advantages. Platinum is usually found as alloys of 80-90% purity in placer deposits, or more rarely combined with arsenic or sulfur. It is indispensable in high-temperature laboratory work, for electrodes, dishes, and electrical contacts that resist chemical attack even when very hot. Platinum is used in dental alloys, and surgical pins. Known as “white gold,” it is used in expensive jewelry and is far more costly than gold. The international primary standards for weight and length are 90% platinum, 10% iridium. An alloy of 76.7% platinum and 23.3% cobalt forms the most powerful permanent magnets known. Platinum has valence 2 or 4 in its compounds, which include many coordination complexes. It and some compounds are useful catalysts, particularly for hydrogenation and in catalytic converters.

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