Allotropes of phosphorus Allotropes of phosphorus Elemental phosphorus can exist in several allotropes, the most common of which are white and red solids. Solid violet and black allotropes are also known. Gaseous phosphorus exists as diphosphorus and atomic phosphorus. White phosphorus, yellow phosphorus or simply tetraphosphorus (P) exists as molecules made up of four atoms in a tetrahedral structure. The tetrahedral arrangement results in ring strain and instability. The molecule is described as consisting of six single P–P bonds. Two different crystalline forms are known. The α form is defined as the standard state of the element, but is actually metastable under standard
Black and white Black and white Black-and-white (B/W or B&W) images combine black and white in a continuous spectrum, producing a range of shades of gray. The history of various visual media has typically begun with black and white, and as technology improved, altered to color. However, there are exceptions to this rule, including black-and-white fine art photography and in motion pictures, many art films. Most early forms of motion pictures or film were black and white. Some color film processes, including hand coloring were experimented with, and in limited use, from the earliest days of motion pictures. The switch from most films