A radioisotope of this element with mass 131 is produced in uranium fission.
This element is generated in situ in a Karl Fischer titration. This element is detected in solution by adding lead (II) [two], forming a bright yellow precipitate. Its binary acid is the strongest common acid. This element is used in redox titrations with thiosulfate, and it gets regenerated in a clock reaction that cycles between colorless and (*) blue. A radioisotope of this element with mass 131 is produced in uranium fission. It is the only diatomic element to be solid at room temperature, though it does sublime. This element is vital to thyroid function, which is why it's added to salt. For 10 points, name this heavy purple halogen with symbol I.
This element is generated in situ in a Karl Fischer titration.
iodine [or I until it is read]