Germanium Selenium

Arsenic (As)

From Wikipedia, the free encyclopediaArsenic is a chemical element with symbol As and atomic number 33. Arsenic occurs in many minerals, usually in conjunction with sulfur and metals, and also as a pure elemental crystal. Arsenic is a metalloid.

Arsenic in the periodic table

Symbol

Atomic number

Group

Period

Block

Element category

Metalloid

Physical properties

Phase at STP

Solid

Density

5.727 g/cm³

Atomic weight

74.9216 u

Melting point

Boiling point

K
°C
°F

Atomic properties

Electronegativity (Pauling Scale)

2.18

Electron affinity

77.65 kJ/mol

Oxidation states

−3, −2, −1, 0, +1, +2, +3, +4, +5
(a mildly acidic oxide)

Ionization energies

1	947 kJ/mol
2	1798 kJ/mol
3	2735 kJ/mol
4	4837 kJ/mol
5	6043 kJ/mol
6	12310 kJ/mol

Electron configuration

Elektronkonfiguration (shorthand)

[Ar] 3d¹⁰ 4s² 4p³

Electron configuration

1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p³

Electrons per shell

2, 8, 18, 5

History

Discovered

815

Discovered by

Middle-Eastern alchemists