As
ARSENIC
(L. arsenicum, Gr. arsenikon, yellow orpiment-identified with arsenikos, male, from the belief that metals were different sexes-Arab. az-zernikh, the orpiment from Persian zerni-zar. gold)
As at. wt. 74.9216
at. no. 33
m.p. 613°C yellow
m.p. 817°C (28 atm.) gray (ordinary metallic)
sp. gr. 1.97 yellow
sp. gr. 5.73 gray
valence -3, 0, +3 or -5.
Electronic configuration
| SHELL |
K |
L |
M |
N |
O |
P |
Q |
| SUB SHELL |
He |
Neon |
Argon |
Krypton |
Xenon |
Radon |
Eka-radon |
| 1s |
2s 2p |
3s 3p |
3d 4s 4p |
4d 5s 5p |
4f 5d 6s 6p |
5f 6d 7s 7p |
| Arsenic
|
1s22s22p63s23p63d104s24p3 |
|
|
|
| Symbol
|
4S3/2 |
Arsenic occurs in two
solid modifications: yellow, and gray or metallic. Gray arsenic,
is the ordinary stable form, and
sublimes at 613°C. Several other allotropic forms of arsenic
are reported in the literature. It is believed that Albertus
Magnus obtained the element in 1250 A.D. In 1649 Schroe-
der published two'methods of preparing~~the element. It is
found native, in the sulfides realgar and' orpiment, as
arsenides and sulfarsenides of heavy metals, as the oxide,
and as arsenates. Mispickel or arsenopyrite (FeSAs) is the
most common mineral, from which on heating the arsenic
sublimes leaving ferrous sulfide. The element is a steel gray,
very brittle, crystalline, semi-metallic solid; it tarnishes in
air, and when heated is rapidly oxidized to arsenous oxide
(As2O3) with the odor of garlic. Arsenic and its compounds
are poisonous. The maximum allowable concentration of
arsenic is recommended to be 0.5 mg/cu. meter of ai?.
Arsenic is also used in bronzing, pyrotechny, and for harden-
ing and improving the sphericity of shot. The most important
compounds are white arsenic (As2O3), the sulfide, Paris
green 3Cu(AsO2)~~Cu(C2H3O2)2, calcium arsenate, and
lead arsenate, the last three being used as agricultural
insecticides and poisons. Marsh's test makes use of the
formation and ready decomposition of arsine (AsH3).
Arsenic is available in high-purity form. It is finding increas-
ing 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.
© 1999 F. Davies
Delphi O.E.M. Co.
All rights reserved
