Argon

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chlorineargon
Ne
Ar
Kr  
 
 
Image:Ar-TableImage.png
Full table
General
Name, Symbol, Number argon, Ar, 18
Chemical series noble gases
Group, Period, Block 18 (VIIIA), 3 , p
Density, Hardness 1.784 kg/m3 (273 K), NA
Appearance Colorless
Atomic properties
Atomic weight 39.948 amu
Atomic radius (calc.) no data (71 pm)
Covalent radius 97 pm
van der Waals radius 188 pm
Electron configuration [Ne]3s2 3p6
e- 's per energy level 2, 8, 8
Oxidation states (Oxide) 0 (unknown)
Crystal structure cubic face centered
Physical properties
State of matter gas (nonmagnetic)
Melting point 83.8 K (−308.7 °F)
Boiling point 87.3 K (−302.4 °F)
Molar volume 22.56 ×10-6 m3/mol
Heat of vaporization 6.447 kJ/mol
Heat of fusion 1.188 kJ/mol
Vapor pressure NA
Speed of sound 319 m/s at 293.15 K
Miscellaneous
Electronegativity no data (Pauling scale)
Specific heat capacity 520 J/(kg*K)
Electrical conductivity no data
Thermal conductivity 0.01772 W/(m*K)
1st ionization potential 1520.6 kJ/mol
2nd ionization potential 2665.8 kJ/mol
3rd ionization potential 3931 kJ/mol
4th ionization potential 5771 kJ/mol
5th ionization potential 7238 kJ/mol
6th ionization potential 8781 kJ/mol
7th ionization potential 11995 kJ/mol
8th ionization potential 13842 kJ/mol
Most stable isotopes
iso NA half-life DM DE MeV DP
36Ar 0.336% Ar is stable with 18 neutrons
38Ar 0.063% Ar is stable with 20 neutrons
39Ar {syn.} 269 y β- 0.565 39K
40Ar 99.6% Ar is stable with 22 neutrons
42Ar {syn} 32.9 y β- 0.600 42K
SI units & STP are used except where noted.

Argon is a chemical element. The symbol for argon is Ar, and its atomic number (or proton number) is 18. It is a noble gas and no electrons or protons can be lost or gained from this atom.

Argon atoms are found in air. About 1% of the Earth's atmosphere (the air around us) is argon.

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