送綦毋潛落第還鄉

鉑(platinum)

金屬化學元素，過渡元素之一，化學符號Pt，原子序數78。是一種非常重的銀白色貴金屬，質地軟，具延展性，熔點很高（1,769℃），耐腐蝕和抗化學反應。一般加入少量的銥形成更硬、更強的合金，而又包括了鉑的優點。通常鉑在砂礦中以合金形式存在，其中包含80～90%的純鉑，或者不多見的是與砷或硫結合在一起。在高溫實驗室的工作中它有不可取代的地位，用作電極、容器以及電接觸，即使在非常熱的情況下仍然能抗化學作用。鉑還用作補牙的合金以及外科手術用的別針。鉑被稱為「白金」，用作貴重的首飾，比金要貴得多。重量和長度的國際標準原型用90%的鉑，10%的銥製成。76.7%鉑與23.3%鈷的合金是已知最強的永久磁體。鉑在它的原子價裡有2價或4價。這些化合物中有許多是配位錯合物。鉑與它的某些化合物都是有用的催化劑，尤其用於氫化作用中，以及用作催化轉化劑。

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.