Fluorine/9/nonmetal/Halogen. In Latin Fluorine means flow or flux. Fluorine is found in all tooth pastes. It is the most reactive of all elements. It can burn metals, glasses, ceramics, Carbon/6/nonmetal, and water. Fluorine was not used until WWII in the atom bomb, which produced Uranium/92/metal/Actinide series.
~Chlorine/17/nonmetal/Halogen. In Greek it means greenish yellow. In small doses it is healing, but in large doses it is fatal. It is never found in nature uncombined. It is mainly combined with Sodium/11/metal/Alkali Metal to form table salt Na+Cl-. Though deadly, it is used to purify water all over the world. Certain species of frogs produce Chlorine on their skin
.~Bromine/35/nonmetal/Halogen. In Greek it means stench. It is the only nonmetallic liquid element on the charts. It evaporates at room temperature and has an irritating effect on the eyes and throat at that state
.~Iodine/53/nonmetal/Halogen. In greek it means violet. At room temperature it vaporizes into a gas with an irritating order.