钠

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钠(sodium)

硷金属族化学元素，化学符号Na，原子序数11。钠是很软的银白色金属。其含量在地球上占第6位，通常以石盐形式存在，不以单体存在於自然界中。钠的化学性质活泼，被作为化学反应物和原料，在冶金学中则作为热交换介质（用於nuclear power发动机和某些引擎中）和钠蒸气灯。钠为维持生命所必需，但鲜少在饮食中缺乏，高血压则与钠摄取过多有关。钠的化合物，其原子价为1者，有许多种在工业上相当重要，包括小苏打、苛性钠、硝石和氯化钠。钠的碳酸盐化合物，为四种最重要的基本化学产品之一，被用於制造玻璃、洗涤剂和清洁剂。以作为家用漂白剂而为人熟知的次氯酸钠，也可用於漂白纸浆和纺织物，用於水的氯气处理，和某些医药用途。硫酸盐则用於硫酸盐制浆法，也用於制造纸板、玻璃和洗涤剂。硫代硫酸盐（亦称hyposulfite或「hypo」）则使用於冲洗底片。

English version：

sodium

Chemical element, one of the alkali metals, chemical symbol Na, atomic number 11. A very soft, silvery-white metal, the sixth most abundant element on earth, it occurs mainly as halite, never free. Extremely reactive, it is used as a chemical reagent and raw material, in metallurgy, as a heat exchanger (in nuclear power generators and certain types of engines), and in sodium-vapor lamps. Sodium is essential for life but rarely deficient in diets; high intake is linked to hypertension. Sodium in compounds, many of great industrial importance (including bicarbonate of soda, caustic soda, saltpeter, and sodium chloride), has valence 1. Sodium carbonate, one of the four most important basic chemical commodities, is used in making glass, detergents, and cleansers. Sodium hypochlorite, familiar as household bleach, is also used to bleach paper pulp and textiles, to chlorinate water, and in some medicines. The sulfate is used in the kraft process and also used to make paperboard, glass, and detergents. The thiosulfate (hyposulfite, or “hypo”) is used in developing photographs.