Arsenic
| Atomic Number: |
33 |
Atomic Radius: |
185 pm (Van der Waals) |
| Atomic Symbol: |
As |
Melting Point: |
~817 °C |
| Atomic Weight: |
74.92 |
Boiling Point: |
603 °C |
| Electron Configuration: |
[Ar]4s23d104p3 |
Oxidation States: |
5, 3, -3 |
History
From the Latin word
arsenicum, Greek
arsenikon.
Elemental arsenic occurs in two solid modifications: yellow, and gray or
metallic, with specific gravities of 1.97, and 5.73, respectively. It
is believed that Albertus Magnus obtained the element in 1250 A.D. In
1649 Schroeder published two methods of preparing the element. Mispickel
arsenopyrite, (FeSAs), is the most common mineral from which, on
heating, the arsenic sublimes leaving ferrous sulfide.
Properties
The element is a steel gray, very brittle, crystalline, semimetallic
solid; it tarnishes in air, and when it is heated it rapidly oxidizes
to arsenous oxide, which smells of garlic. Arsenic and its compounds are
poisonous.
Uses
Arsenic is used in bronzing, pyrotechny, and for hardening and
improving the sphericity of shot. The most important compounds are white
arsenic, the sulfide, Paris green, calcium arsenate, and lead arsenate;
the last three have been used as agricultural insecticides and poisons.
Marsh's test makes use of the formation and ready decomposition of
arsine. Arsenic is finding increasing uses as a doping agent in
solid-state devices such as transistors. Gallium arsenide is used as a
laser material to convert electricity directly into coherent light.
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