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
Naming of chemical elements the 1970s (when the elements were discovered) to the 1990s, when the International Union of Pure and Applied Chemistry (IUPAC) created a tentative list of the element names for elements 104 to 109. The Americans, however, refused to agree with these names because seaborgium was not in the list. Thus, IUPAC reconsidered, and in 1996 named element 105 dubnium and element 106 seaborgium. When a pure element, comprising only one type of atom, nevertheless exists in multiple forms (allotropes) with different structure and properties, they are generally given different names; for example graphite and diamond are both forms of the