18
39.95
Ar
Argon
Identification
CAS Number: 7440-37-1
Discovery Year: 1894
Discoverer: Sir William Ramsey, Baron Rayleigh
Discovery Location: Scotland
Properties
Atomic Dimensions
Atomic Radius: 71 pm →
Atomic Radius (Rahm): 197 pm
Covalent Radius: 106 pm →Van der Waals Radius: 188 pm
Atomic Volume: 24.2 cm³/mol
Lattice Constant: 5.26 Å
Thermodynamics
Electronic Structure
Electron Config: [Ne] 3s2 3p6
Block: p
Period: 3 →Group: 18 →Electron Affinity: -11.5 eV →Oxidation States: 0
Abundance & Geochemistry
Crust Abundance: 3.5 mg/kg
Sea Abundance: 0.45 mg/L
Geochemical Class: volatile
Goldschmidt Class: atmophile
About
Argon is a colorless, odorless noble gas that makes up about 1% of Earth's atmosphere. It is used in welding, light bulbs, and as an inert atmosphere.
Isotopes
Ar-40 40 99.60%
Ar-36 36 0.3336%
Ar-38 38 0.0629%
