Template:Infobox arsenic

Arsenic,  ₃₃As

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General properties
Pronunciation	Template:Infobox element/pronunciation
Allotropes	grey (most common), yellow, black
Appearance	metallic grey
Standard atomic weight (Ar, standard)	Template:Infobox element/standard atomic weight
Mass number	Template:Infobox element/symbol-to-most-stable-isotope (most stable isotope)
Arsenic in the periodic table
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Atomic number (Z)	33
Group	Template:Infobox element/group
Period	period 4
Block	p-block
Element category	Template:Infobox element/category format
Electron configuration	[Ar] 3d10 4s2 4p3
Electrons per shell	2, 8, 18, 5
Physical properties
Phase at STP	solid
Sublimation point	887 K ​(615 °C, ​1137 °F)
Density (near r.t.)	5.727 g/cm3
when liquid (at m.p.)	5.22 g/cm3
Triple point	1090 K, ​3628 kPa
Critical point	1673 K, ? MPa
Heat of fusion	grey: 24.44 kJ/mol
[[Enthalpy of vaporization|Heat of Template:Engvar]]	34.76 kJ/mol (?)
Molar heat capacity	24.64 J/(mol·K)
[[Vapor pressure|Template:Engvar pressure]] Template:Infobox element/vapor pressure table
Atomic properties
Oxidation states	Template:Infobox element/symbol-to-oxidation-state
Electronegativity	Pauling scale: 2.18
[[Ionization energy|Template:Engvar energies]]	1st: 947.0 kJ/mol 2nd: 1798 kJ/mol 3rd: 2735 kJ/mol (more)
Atomic radius	empirical: 119 pm
Covalent radius	119±4 pm
Van der Waals radius	185 pm
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Other properties
Crystal structure	​Template:Infobox element/crystal structure Template:Infobox element/crystal structure
Thermal expansion	5.6 µm/(m·K) (at r.t.)
Thermal conductivity	50.2 W/(m·K)
Electrical resistivity	333 nΩ·m (at 20 °C)
Magnetic ordering	diamagnetic
Magnetic susceptibility	−5.5·10−6 cm3/mol
Young's modulus	8 GPa
Bulk modulus	22 GPa
Mohs hardness	3.5
Brinell hardness	1440 MPa
CAS Number	7440-38-2
History
Discovery	before 300 CE
Main isotopes of arsenic
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