Symbol: As
Atomic Number: 33
Atomic Weight: 74.92159
Element Classification: Semimetallic
Discovered By: Known to the ancients.
Discovery Date: n/a (Unknown)
Name Origin: Greek: arsenikon; Latin: arsenicum, (both names for yellow pigment).

Density (g/cc): 5.73 (grey arsenic)
Melting Point (K): 1090
Boiling Point (K): 876
Appearance: Steel gray, brittle semimetal
Atomic Radius (pm): 139
Atomic Volume (cc/mol): 13.1
Covalent Radius (pm): 120
Ionic Radius: 46 (+5e) 222 (-3e)
Specific Heat (@20C J/g mol): 0.328
Fusion Heat (kJ/mol): n/a
Evaporation Heat (kJ/mol): 32.4
Thermal Conductivity (@25C W/m K):
Debye Temperature (K): 285.00
Pauling Negativity Number: 2.18
First Ionizing Energy (kJ/mol): 946.2
Oxidation States: 5, 3, -2
Electronic Configuration: [Ar] 3d10 4s2 4p3
Lattice Structure: Rhombohedral (RHL)
Lattice Constant (): 4.130
Lattice C/A Ratio: n/a

Mineral Hardness [no units]: 3.5
Brinell Hardness [/MN m-2]: 1440

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