What is the common name for P2O3?

The common name for P2O3 is indeed diphosphorus trioxide. This nomenclature comes from the composition of the compound, which consists of two phosphorus (P) atoms and three oxygen (O) atoms. In chemical nomenclature, the prefix "di-" is used to indicate that there are two phosphorus atoms present. The suffix "trioxide" indicates that there are three oxygen atoms.

This systematic approach helps in clearly conveying the molecular structure of the compound. While "phosphorus trioxide" might seem plausible, it does not specify the number of phosphorus atoms, which is fundamental in understanding the compound's makeup. Similarly, "tetraphosphorus trioxide" would suggest that there are four phosphorus atoms, which is incorrect for P2O3. Lastly, "phosphorus pentoxide" refers to P2O5, which again would be distinct from P2O3 since it contains five oxygen atoms.

Using these prefixes not only facilitates the identification and differentiation of chemical species but also adheres to the conventions set forth in chemical nomenclature, ensuring clarity and precision in communication.