Why is there such a big difference between white phosphorus in a regular tetrahedron shape and red phosphorus, which consists of single atoms?
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P is used for semiconductor doping, and one day a colleague suddenly asked me what the difference between white phosphorus and red phosphorus is I, who study chemistry, was completely confused; even after searching on Baidu, I didn’t understand what was going on. Why, even though it is phosphorus in its elemental form, do different structures result in such significant differences in chemical properties?
White phosphorus, or yellow phosphorus, has a tetrahedral structure composed of four phosphorus atoms. Since each phosphorus atom forms bonds through SP3 hybridization, with a pair of lone electrons located outside the tetrahedron, it is highly reactive and readily reacts with oxidizing non-metal elements; as a result, its properties are unstable. The phosphorus atoms in red phosphorus are SP2-hybridized, and they are bonded to each other through multi-electron large Π bonds, similar to the micrographite structure in activated carbon, resulting in stable chemical properties. There is also black phosphorus, which has a purely graphite structure, is more stable in properties, and can also conduct electricity. The above explanation is based on my knowledge of inorganic chemistry and valence bond theory from over 20 years ago, and it is not necessarily correct.