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
Violet light Violet light Though the violet color is normally composed of blue and red light, violet color can also be monochromatic, composed only by violet light. Combinations of red and blue lights and monochromatic light of wavelength smaller than blue produce a similar effect for the human eye due to a second resonancy of the red-sensitive cone cells. Composed-light violet shows two colors when decomposed. Violet light from the rainbow, which can be referred as spectral violet, is composed only by a short wavelength instead. This monochromatic violet light occupies its own place at the end of the visible spectrum, and