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
Violet-crowned hummingbird Violet-crowned hummingbird The violet-crowned hummingbird ("Amazilia violiceps") is a medium-sized hummingbird. It is 10 cm long and weighs approximately 5 g. The bird is best distinguished by its violet-colored cap, from where it gets its name. Adults are colored predominantly a dark olive green for their upperparts and tail. The underparts are predominantly white. The bill of the male is straight and very slender. It is red in coloration, and shows a black tip. The female is less colorful than the male. The breeding habitat is in arid scrub of southeastern Arizona in the United States to southwestern Mexico, (the