Template:Infobox argon

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18 chlorine ← argon → potassium Ne ↑ Ar ↓ Kr Periodic table - Extended periodic table
General
Name, symbol, number	argon, Ar, 18
Chemical series	noble gases
Group, period, block	18, 3, p
Appearance	colorless
Standard atomic weight	39.948(1) g·mol−1
Electron configuration	[Ne] 3s2 3p6
Electrons per shell	2, 8, 8
Physical properties
Phase	gas (At room temperature)
Density	(0 °C, 101.325 kPa) 1.784 g/L
Melting point	83.80 K (−189.35 °C, −308.83 °F)
Boiling point	87.30 K (−185.85 °C, −302.53 °F)
Triple point	83.8058 K (-189°C), 69 kPa
Critical point	150.87 K, 4.898 MPa
Heat of fusion	1.18 kJ·mol−1
Heat of vaporization	6.43 kJ·mol−1
Specific heat capacity	(25 °C) 20.786 J·mol−1·K−1
Vapor pressure P/Pa 1 10 100 1 k 10 k 100 k at T/K   47 53 61 71 87
Atomic properties
Crystal structure	cubic face centered
Oxidation states	0
Electronegativity	no data (Pauling scale)
Ionization energies (more)	1st: 1520.6 kJ·mol−1
	2nd: 2665.8 kJ·mol−1
	3rd: 3931 kJ·mol−1
Atomic radius	71 pm
Atomic radius (calc.)	71 pm
Covalent radius	97 pm
Van der Waals radius	188 pm
Miscellaneous
Magnetic ordering	nonmagnetic
Thermal conductivity	(300 K) 17.72x10-3  W·m−1·K−1
Speed of sound	(gas, 27 °C) 323 m/s
CAS registry number	7440–37–1
Selected isotopes
Main article: Isotopes of argon iso NA half-life DM DE (MeV) DP 36Ar 0.337% 36Ar is stable with 18 neutrons 37Ar syn 35 d ε 0.813 37Cl 38Ar 0.063% 38Ar is stable with 20 neutrons 39Ar syn 269 y β- 0.565 39K 40Ar 99.600% 40Ar is stable with 22 neutrons 41Ar syn 109.34 min β- 2.49 41K 42Ar syn 32.9 y β- 0.600 42K
References
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