Chemical element named mendelevium in honor of D.I. Mendeleev, the first to arrange the elements in a periodic manner. Most recently, the synthesis of element 118 (since named oganesson) was reported in October 2006, and the synthesis of element 117 (tennessine) was reported in April 2010. Ten materials familiar to various prehistoric cultures are now known to be chemical elements: Carbon, copper, gold, iron, lead, mercury, silver, sulfur, tin, and zinc. Three additional materials now accepted as elements, arsenic, antimony, and bismuth, were recognized as distinct substances prior to 1500 AD. Phosphorus, cobalt, and platinum were isolated before 1750. Most of the
Chemical Weapons Convention Chlorine gas is highly toxic, but being a pure element and extremely widely used for peaceful purposes, is not officially listed as a chemical weapon. Certain state-powers (e.g. the Assad regime of Syria) continue to regularly manufacture and implement such chemicals in combat munitions. Although these chemicals are not specifically listed as controlled by the CWC, the use of any toxic chemical as a weapon (when used to produce fatalities solely or mainly through its toxic action) is in-and-of itself forbidden by the treaty. Other chemicals, such as white phosphorus, are highly toxic but are legal under the CWC when