Q: At room temperature, chlorine is a yellowish gas, bromine is a brown liquid, and iodine is a shiny blue-black solid. Why are these elements considered similar enough to group together on the periodic table?

Flexi Says: The elements of Group VIIA (new Group 17 - fluorine, chlorine, bromine, iodine, and astatine) are called the halogens (tan column). The term “halogen” means “salt-former” because these elements will readily react with alkali metal and alkaline earth metals to form halide salts. The halogens all have the general electron configuration ns2np5, giving them seven valence electrons. They are one electron short of having the full outer s and p sublevel, which makes them very reactive.