The halogen whose name comes from the Greek word for “violet” is iodine. Its symbol is I and its atomic number is 53; the name refers to the striking violet color of iodine vapor.
French chemist Bernard Courtois discovered iodine in 1811 while processing seaweed ash for saltpeter production. When he added sulfuric acid to the waste mixture, a cloud of violet vapor appeared and condensed into dark crystals. Joseph Louis Gay-Lussac later recognized it as a new element and proposed the name based on the Greek word iodes, meaning violet.
Iodine belongs to group 17, the halogens, alongside fluorine, chlorine, bromine, astatine, and tennessine. It is the heaviest stable halogen and is less reactive than the lighter members of the group.
The answer choices can be confusing because fluorine, chlorine, and bromine are also halogens. However, only iodine has the violet-based name, matching both the etymological clue and the color of its vapor.