Atom Model


Name of element: Arsenic

Symbol: As

Atomic Number: 33

Atomic Mass: 74.92 (approx. 75)

Electron Configuration: 2-8-18-5

Location on periodic table: Group 15

Period & Family: It’s period numbers 4 and it is in the family of non-metals/metalloids.

Radioactivity: none
Color: dark gray to black.


Although arsenic compounds were mined by the early Chinese, Greek and Egyptian civilizations, it is believed that arsenic itself was first identified by Albertus Magnus, a German alchemist, in 1250.

o Natural Occurrence:
Arsenic is found in nature at low levels, mostly in compounds with oxygen, chlorine, and sulfur. These are inorganic arsenic compounds. Arsenic in plants and animals combines with carbon and hydrogen.

Arsenic and its compounds are poisonous. They have been used to make rat poison and some insecticides. Small amounts of arsenic are added to germanium to make transistors. Gallium arsenide can produce laser light directly from electricity. Its organic compounds are used to treat syphilis and yaws), and it can be combined with other elements to form strong poisons. Arsenic has no smell or special taste.

o Common Uses:
Domestic: termite control, timber preservative, wallpaper, paints, and ceramics.
Agricultural: herbicides for weeds, grasses, prickly pears, and burrs; rodent control; organic arsenicals are currently being fed to poultry and pigs to promote growth and increase feed efficiency, and in a tonic for horses and cattle.
Industrial: Gold mining; added to alloys for strength at high temperatures, harder bullets.

Preparation of Element: Today, most commercial arsenic is obtained by heating arsenopyrite.

Physical Properties: Melting point: 817C or 1503F

Boiling point: 614°C or 1137°F

Density: 5.776 grams per cubic centimeter

Chemical Properties: The chemical properties of arsenic are that it can not mix with halogenated compounds, rhubidium and carbides. Arsenic is a poison and the fumes are very toxic. Arsenic doesn’t evaporate, but most of its compounds can dissolve in water. It never "breaks down", but it can change from one form to another.