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Argon

Non-Metalgaseous
Symbol: Ar
Atomic number: 18
Atomic mass: 39.948
Group: Noble Gas
CAS-number: 7440-37-1

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Physical data
Isotopes
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Neon
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Physical data

Electronic dataThermal dataSteric data
Shells: 2, 8, 8
Orbitals: [Ne] 3s2 3p6
Electronegativity: --, 3.2
1. Ionization potential: 15.7596 eV
2. Ionization potential: 27.629 eV
3. Ionization potential: 40.74 eV
Oxidation states: 0
Electrical conductivity: --
Melting point: -189.2 °C
Boiling point: -185.7 °C
Specific heat: 0.520 J/gK
Heat of fusion: 1.188 kJ/mol
Heat of vaporization: 6.447 kJ/mol
Thermal conductivity: 0.0001772 W/cmK
Atomic radius: 0.88 Å
Ionic radius: -- Å
Covalent radius: 0.98 Å
Atomic volume: 23.9 cm³/mol
Density (293 K): 0.0017824 g/cm³
Crystal structure: cubic face centered
cubic face centered

Isotopes

NuclideAbundance [%]MassSpinHalflifeDecay modeDecay tree
36Ar 0.337 34.9675 0 -- --
37Ar 0 36.9667 3/2 35.0d EC View
38Ar 0.063 37.9627 0 -- --
39Ar 0 38.964 7/2 269y β- View
40Ar 99.6 39.9624 0 -- --
41Ar 0 41 7/2 1.82h β- View

Other info

Name origin:Greek: argos (inactive)
Description:Colorless, odorless, tasteless noble gas. It is the third most abundant element in the earth's atmosphere and makes up about 1%.
Discovered by:Sir William Ramsey, Baron Rayleigh
Year:1894
Place:Scotland
Sources:Continuously released into the air by decay of radioactive potassium-40. Pure form is obtained from fractional distillation of liquid air.
Use(s):Used in lighting products. It is often used in filling incandescent light bulbs. Some is mixed with krypton in fluorescent lamps. Crystals in the semiconductor industry are grown in argon atmospheres.