33
74.92
As
Arsenic
Identification
CAS Number: 7440-38-2
Discoverer: Known to the ancients.
Properties
Atomic Dimensions
Atomic Radius: 115 pm →
Atomic Radius (Rahm): 231 pm
Covalent Radius: 119 pm →Van der Waals Radius: 185 pm
Metallic Radius: 121 pm
Atomic Volume: 13.1 cm³/mol
Lattice Constant: 4.13 Å
Thermodynamics
Melting Point: 1090 K →Boiling Point: 876 K →Specific Heat: 0.328 J/(g·K) →Heat of Vaporization: 32.4 kJ/mol →
Heat of Formation: 302.5 kJ/mol
Electronic Structure
Electron Config: [Ar] 3d10 4s2 4p3
Block: p
Period: 4 →Group: 15 →Electronegativity: 2.18 →Electron Affinity: 0.804 eV →Oxidation States: -3, +3, +5
Abundance & Geochemistry
Crust Abundance: 1.8 mg/kg
Sea Abundance: 0.0037 mg/L
Geochemical Class: semi-volatile
Goldschmidt Class: chalcophile
About
Metalloid element of group 15. There are three allotropes, yellow, black, and grey. Reacts with halogens, concentrated oxidizing acids and hot alkalis. Albertus Magnus is believed to have been the first to isolate the element in 1250.
Isotopes
As-75 75 100.00%