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
Lacul cu Nămol Lacul cu Nămol Lacul cu Nămol, also called (Lacul) Balta cu Nămol, is a natural salt lake in the town of Ocna Sibiului, Sibiu County, Transylvania, Romania. It is one of the many lakes of the Ocna Sibiului mine, a large salt mine which has one of the largest salt reserves in Romania. In Romanian, "Lacul cu Nămol" means "the Lake with Mud" . The other name of the lake, Balta cu Nămol, means the Pond with Mud. The lake was formed after an excavation of the salt's cover. Lacul cu Nămol and Lacul Negru are the only lakes of