氯化钠Sodium chloride

NaCl 晶体中每个 Na⁺ 被六个 Cl⁻ 包围成八面体，反之亦然，配位数 6:6，晶胞参数 564 pm，每个晶胞含 4 个 NaCl。这种“岩盐型结构”是许多 AB 型离子晶体（MgO、AgCl、KBr 等）的原型。NaCl 的晶格能约 787 kJ/mol，可由玻恩-哈伯循环计算。

In the crystal each Na⁺ is surrounded octahedrally by six Cl⁻ and vice versa (6:6 coordination); the cubic cell edge is 564 pm and holds four formula units. This rock-salt structure is the prototype for many AB ionic solids such as MgO, AgCl and KBr. Its lattice energy, about 787 kJ/mol, can be calculated with the Born–Haber cycle.

盐是人类最早的贸易品之一，中国在约公元前 6000 年已煮海水制盐，四川自贡的深井卤水开采可追溯到汉代。1913 年布拉格父子用 X 射线衍射测定了 NaCl 晶体结构，这是最早被解析的晶体结构之一，证明了离子晶体中不存在独立的 NaCl 分子。

Salt was one of humanity's earliest trade goods; in China seawater was boiled for salt by about 6000 BCE, and deep brine wells at Zigong in Sichuan date back to the Han dynasty. In 1913 the Braggs solved the NaCl structure by X-ray diffraction, one of the first crystal structures determined, showing that the crystal contains no separate NaCl molecules.

全球年产约 3 亿吨，其中大部分用于电解饱和食盐水生产氯气、氢气和氢氧化钠，以及索尔维法和侯氏制碱法生产纯碱。食盐是重要的调味品和防腐剂，0.9% 的氯化钠溶液为生理盐水；冬季也用于道路除冰。

World output is about 300 million tonnes a year, most of it electrolysed as brine to chlorine, hydrogen and sodium hydroxide or used to make soda ash by the Solvay and Hou processes. Salt is a key seasoning and preservative, 0.9% NaCl is physiological saline, and it de-ices roads in winter.