When exposed to air, arsenic quickly tarnishes to a yellow color, eventually turning black. Arsenic is a well-known poison. It is used as a weed killer and insecticide, being commonly sprayed on fruit to ward off damage by insects. Doses small as one-tenth of a gram of arsenic can be fatal to humans. Minute traces can actually stimulate the production of red blood cells. Although a poison, arsenic compounds have had a history of producing useful medical products. Many skin diseases have been effectively treated with some of these compounds, as has ameobic dysentery. Newer and potentially less dangerous treatments have replaced many of these compounds.
Arsenic has become a material of great importance in the world of solid-state electronics. Small amount of arsenic are now added to such semiconductors as germanium and silicon to transform them into transistors. Its also forms a compound with gallium, gallium arsenide (GaAs), that can transform electricity directly into light. This is used to produce light-emitting diodes, or LEDs.
- Name, Symbol, Number: arsenic, As, 33
- Chemical series: Metalloid
- Phase: solid
- Melting point: 817°c
- Boiling point: 613°c
- Density: 5.73g/cm3
- Atomic weight: 74.92159
- Electrons per shell: 2, 8, 18, 5
