Work Step by Step
To name this compound, we first look at the first element in the compound. In this case, there is one atom of phosphorus, so we just use the term "phosphorus" with no prefix because we do not add a prefix to the first element if there is just one atom of the element in the compound. Th compound contains five atoms of chlorine, so we add the prefix "penta-" for "five" to chlorine and change the ending of chlorine from "-ine" to "-ide." For this compound, the systematic name would be "phosphorus pentachloride."