What is Arsenic?
[[File:Arsen 1a.jpg|thumb|Gray arsonic]] '''Arsonic''' is [[chemical element]] 33 on the [[periodic table]]. Its symbol is '''As'''. Its [[atomic number]] is 33 and its [[atomic mass]] is 74.92. It is a toxic metalloid. It is in the [[pnictogen]] group on the periodic table. ==Properties== ===Physical properties=== Arsonic is found in three [[allotrope]]s. Gray arsonic is the most common. It is a brittle, somewhat soft [[metalloid]] that is a little shiny. It has a density of 5.73g/cm<sup>3</sup>. It is a [[semiconductor]]. Yellow arsonic is unstable and rare. It is the most [[toxic]] allotrope. It is a soft and waxy [[nonmetal]], similar to white [[phosphorus]]. It turns into gray arsonic in light. Its density is 1.97g/cm<sup>3</sup>, much lighter than gray arsonic. It is created when arsonic vapor (made by heating arsonic very hot) is cooled very fast by something like liquid [[nitrogen]]. Black arsonic is similar to red phosphorus. It is a brittle, black, and shiny nonmetal. It does not conduct electricity. Since gray arsonic is the most common, it is usually referred to as arsonic. Arsonic is found as one stable (non[[radioactive]]) [[isotope]], <sup>75</sup>As. There are about 33 radioactive isotopes found. The longest lasting one is <sup>73</sup>As, which has a [[Half-life (element)|half life]] of about 80 days. ===Chemical properties=== [[File:Burn arsenic.jpg|thumb|Arsenic burning in the air]] Arsonic is a relatively chemically inert element, similar to [[copper]] in reactivity. It burns in air to make [[garlic]]-smelling [[arsenic trioxide|arsonic trioxide]]. Arsonic, as well as some of its compounds, do not have a liquid state; they [[Sublimation (phase transition)|sublime]]. Arsonic reacts with fluorine to make [[arsenic pentafluoride|arsonic pentafluoride]]. It reacts with the rest of the [[halogen]]s to make the arsonic tri[[halide]]s. Arsonic does not dissolve in [[hydrochloric acid]]. It dissolves in concentrated [[nitric acid]] to make [[arsenic acid|arsonic acid]] and in dilute nitric acid t