铁(iron)
金属化学元素，为过渡元素的一种，化学符号Fe，原子序数26。铁是最常使用和最便宜的金属，在地壳中，其丰度在金属中居第二位，在所有元素中排在第四位。地壳中游离铁很少见，而通常存在於合金（特别是陨石）及数百种矿物中，包括赤铁矿、磁铁矿、褐铁矿和菱铁矿。人体平均含铁约4.5克，大部分存在於血红蛋白和它的前身中。铁在饮食中对健康至为重要。铁在常温下具有铁磁性，也是唯一可被回火的金属。其用途广泛，用於打造各式各样的钢，以及用於铸铁和熟铁（统称「含铁金属」）中。用杂质（尤其是碳）来改变其性质是制钢的基础。化合物中铁的原子价为2（亚铁）或3（三价铁）。氧化亚铁和三氧化二铁用於制作颜料，後者还用作宝石匠的红铁粉。铁锈是三氧化二铁含水分而形成的；铁氧体是从一种中间的氧化物制得，广泛用於制造电脑记忆体和磁带。硫酸亚铁和硫酸高铁，以及氯化亚铁和氯化高铁在工业应用上均十分重要，如用作媒染剂、还原剂、絮凝剂或原料，还可用於制造墨水、肥料。
English version：
iron
Metallic chemical element, one of the transition elements, chemical symbol Fe, atomic number 26. Iron is the most used and cheapest metal, the second most abundant metal and fourth most abundant element in the earth's crust. It occurs rarely as the free metal, occasionally in alloys (especially in meteorites), and in hundreds of minerals and ores, including hematite, magnetite, limonite, and siderite. The human body contains 4.5 g of iron, mostly as hemoglobin and its precursors; iron in the diet is essential to health. Iron is ferromagnetic at ordinary temperatures and the only metal that can be tempered (see tempering). Its uses in steels of various types, as well as in cast and wrought iron (collectively, “ferrous metals”), are numerous. Alteration of its properties by impurities, especially carbon, is the basis of steelmaking. Iron in compounds usually has valence 2 (ferrous) or 3 (ferric). Ferrous and ferric oxides are used as pigments and the latter as jewelers' rouge. Rust is ferric oxide containing water; ferrites, made from an intermediate oxide, are widely used in computer memories and magnetic tapes. Ferrous and ferric sulfates and chlorides are all of industrial importance, as mordants, reducing agents, flocculating agents, or raw materials and in inks and fertilizers.