<P> There are no stable isotopes of astatine . However, there are three naturally occurring radioactive isotopes of astatine produced via radioactive decay of uranium, neptunium, and plutonium . These isotopes are astatine - 215, astatine - 217, and astatine - 219 . A total of 31 isotopes of astatine have been discovered, with atomic masses ranging from 193 to 223 . </P> <P> Approximately six million metric tons of the fluorine mineral fluorite are produced each year . Four hundred - thousand metric tons of hydrofluoric acid are made each year . Fluorine gas is made from hydrofluoric acid produced as a by - product in phosphoric acid manufacture . Approximately 15,000 metric tons of fluorine gas are made per year . </P> <P> The mineral halite is the mineral that is most commonly mined for chlorine, but the minerals carnallite and sylvite are also mined for chlorine . Forty million metric tons of chlorine are produced each year by the electrolysis of brine . </P> <P> Approximately 450,000 metric tons of bromine are produced each year . Fifty percent of all bromine produced is produced in the United States, 35% in Israel, and most of the remainder in China . Historically, bromine was produced by adding sulfuric acid and bleaching powder to natural brine . However, in modern times, bromine is produced by electrolysis, a method invented by Herbert Dow . It is also possible to produce bromine by passing chlorine through seawater and then passing air through the seawater . </P>

How many atoms are in each molecule of a halogen