Return to the Main CHEMystery Page.
Return to the Periodic Table of the Elements

Element 18 - Argon (Ar) sound

From argon, or inactive; discovered 1894. The most abundant of noble gases, argon makes up 0.934 percent of the air. Its industrial forte is in welding: it provides an inert atmosphere in which welded metals will not burn. It is also the gas that files ordinary incandescent light bulbs.

Properties

Atomic Number: 18
Atomic Weight: 39.948
Electron Configuration (at ground state): 1s22s22p63s23p6
Oxidation States (Bold most stable): 0
Boiling Point (K): 87.45
Melting Point (K): 83.95
Density (at STP -- g/l): 1.784
Atomic Volume (liquid state at boiling point -- cm3/mol) 24.2
Number of stable isotopes: 3
Mass Number (Bold naturally occurring) -- Half-Life -- Disintigration Type: 37 -- 35.02 days -- orbital electron capture
39 -- 265 years -- beta particle (electron) emission
Covalent Radius (Å): 0.98
Atomic Radius (Å): 0.88
First Ionization Potential (V): 15.759
Specific Heat Capacity (at 300K -- J g-1 K-1): 0.520
Heat of Vaporization (kJ/mol): 6.506
Heat of Fusion (kJ/mol): 1.188
Thermal Conductivity (at 300K -- W m-1 K-1): 0.0177
Crystal Structure: Cubic, face centered