Arsenic
For LEDs.
| Atomic Number: |
33 |
| Atomic Symbol: |
As |
| Atomic Weight: |
74.9216 |
| Electron Configuration: |
[Ar]4s23d104p3 |
History
(L. arsenicum, Gr. arsenikon, yellow orpiment, identified with arenikos, male, from the
belief that metals were different sexes; Arabic, Az-zernikh, the orpiment from Persian
zerni-zar, gold) 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 heated is rapidly oxidized to arsenous oxide with the odor 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.
Sources: CRC Handbook of Chemistry
and Physics and the American Chemical Society.
Last Updated: 12/19/97, CST Information Services Team
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