Arsenic Arsenic Arsenic is a chemical element with symbol As and atomic number 33. Arsenic occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic is a metalloid. It has various allotropes, but only the gray form, which has a metallic appearance, is important to industry. The primary use of arsenic is in alloys of lead (for example, in car batteries and ammunition). Arsenic is a common n-type dopant in semiconductor electronic devices, and the optoelectronic compound gallium arsenide is the second most commonly used semiconductor after doped silicon. Arsenic and its
Fullerene chemistry one or more bonds are removed chemically exposing an orifice. In this way it is possible to insert into it small molecules such as hydrogen, helium or lithium. The first such open-cage fullerene was reported in 1995. In endohedral hydrogen fullerenes the opening, hydrogen insertion and closing back up has already been demonstrated. In heterofullerenes at least one carbon atom is replaced by another element. Based on spectroscopy, substitutions have been reported with boron (borafullerenes), nitrogen (azafullerenes), oxygen, arsenic, germanium, phosphorus, silicon, iron, copper, nickel, rhodium and iridium. Reports on isolated heterofullerenes are limited to those based on nitrogen and