Iodine is a trace element found in seawater and in some soils ... but they learned that iodine can essentially be sprayed on table salt. Iodized salt first became available in 1924.

Fluorine and chlorine are gases. Bromine is one of only two liquid elements. Iodine is solid. They exist as diatomic molecules - they have two atoms in each molecule. As you go down the group the ...