The Deacon oxidation process is one method of producing this element, which is produced on a large scale by performing electrolysis on brine, which also produces caustic soda and hydrogen gas.
The Miller process of gold purification involves blowing this substance into the impure mixture, and a radioactive isotope of this element can be generated by muon capture in calcium-40. In mass spectrometry of compounds containing this element, an M plus 2 compound peak of one-half the intensity of the M peak is obtained.  The Deacon oxidation process is one method of producing this element, which is produced on a large scale by performing electrolysis on brine, which also produces caustic soda and hydrogen gas. This element is incorporated into organic compounds by a reagent which contains five atoms of it bonded to a single phosphorous atom, and mixing acids and bleach can release the gaseous form of this compound, which was the first chemical weapon used. For 10 points, name this element with atomic mass 35.45, atomic number 17, and symbol Cl.
The Miller process of gold purification involves blowing this substance into the impure mixture, and a radioactive isotope of this element can be generated by muon capture in calcium-40.
{Chlorine} (Accept {Cl2} or {chlorine gas} at any {time})