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
Red-violet lies halfway between green and spring green. It is very close to sea green, but highly saturated, and of a bright hue. In some traditional usage, red-violet is the name given to an intermediate or tertiary color that, along with yellow-orange (gold) and also green-blue (cyan), forms a color wheel triad group. Most contemporary usage, however, would list magenta as the name for the tertiary color in question. Red-violet or pigment purple (pigment red-violet) represents the way the color purple (red-violet) was normally reproduced in pigments, paints, or colored pencils in the 1950s on an old-fashioned RYB color wheel. This