Hazard characteristics of aluminum trichloride: it is easy to hydrolyze, react with water, generate heat, and release toxic corrosive gas (hydrogen chloride).

它的蒸气是缔合的双分子。氯和强热的金属铝反应即得无水氯化铝。溶于许多有机溶剂。在空气中极易吸取水分而发生烟雾。水溶液呈酸性。水溶液中析出的晶体是六水合物而不能得到无水氯化铝（AlCl3），因为进一步蒸干会导致铝离子完全水解，因此后者只能通过铝和氯气直接反应获得。无水氯化铝在石油工业中及其他某些有机合成反应中用作催化剂。

Its vapor is a bimolecular association. Anhydrous aluminum chloride is obtained by the reaction of chlorine with strong heat metal aluminum. Soluble in many organic solvents. It is very easy to absorb moisture in the air and produce smoke. The aqueous solution is acidic. The crystal precipitated from aqueous solution is hexahydrate, but anhydrous aluminum chloride (AlCl3) can not be obtained, because further evaporation will lead to complete hydrolysis of aluminum ions, so the latter can only be obtained by direct reaction of aluminum and chlorine. Anhydrous aluminum chloride is used as a catalyst in petroleum industry and some other organic synthesis reactions.

三氯化铝的价键性质：铝为sp3轨道杂化，分子中存在桥键，和乙硼烷的结构相似（AlCl3的分子式其实是Al2Cl6），这样可以让Al达到八电子稳定结构。但Al2Cl6可以和路易斯碱作用，例如Al2Cl6+2Cl-→2[AlCl4]-。产物相当于AlCl3单体和路易斯碱的加合物，因此氯化铝仍然是一种非常好的路易斯酸（路易斯酸性较强），利用其性质常用来做有机反应的催化剂。

The valence bond properties of aluminum trichloride: aluminum is SP3 orbital hybrid, and there is bridge bond in the molecule, which is similar to the structure of ethylborane (the molecular formula of AlCl3 is al2cl6), so that Al can reach the eight electron stable structure. However, al2cl6 can interact with Lewis bases, such as al2cl6 + 2Cl - → 2 [alcl4] -. The product is equivalent to the adduct of AlCl3 monomer and Lewis base, so aluminum chloride is still a very good Lewis acid (strong Lewis acid), which is often used as a catalyst for organic reactions.

需要注意一点的是，虽然三氯化铝是由金属原子和非金属原子化合而成，但氯化铝（AlCl3）并不属于离子化合物，而属于共价化合物。这是中学化学中一个典型的由金属和活泼非金属元素组成的共价化合物。因为铝为sp3轨道杂化，分子中存在桥键，和乙硼烷的结构相似（AlCl3的分子式其实是Al2Cl6），这样可以让Al达到八电子稳定结构。所以AlCl3是共价化合物，不是离子化合物！

It should be noted that aluminum chloride (AlCl3) is not an ionic compound, but a covalent compound, although it is composed of metal atoms and non-metal atoms. This is a typical covalent compound composed of metal and active nonmetal elements in middle school chemistry. Because aluminum is SP3 orbital hybrid, there is a bridge bond in the molecule, which is similar to the structure of borane (the molecular formula of AlCl3 is al2cl6), so that Al can reach the eight electron stable structure. So AlCl3 is a covalent compound, not an ionic compound!