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Pronunciation | (AR-gon) |
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Appearance | colorless gas exhibiting a lilac/violet glow when placed in an electric field |
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Group | group 18 (noble gases) |
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Period | period 3 |
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Block | p-block |
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Electron configuration | [Ne] 3s2 3p6 |
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Electrons per shell | 2, 8, 8 |
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Phase at STP | gas |
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Melting point | 83.81 K (−189.34 °C, −308.81 °F) |
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Boiling point | 87.302 K (−185.848 °C, −302.526 °F) |
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Density (at STP) | 1.784 g/L |
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when liquid (at b.p.) | 1.3954 g/cm3 |
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Triple point | 83.8058 K, 68.89 kPa[3] |
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Critical point | 150.687 K, 4.863 MPa[3] |
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Heat of fusion | 1.18 kJ/mol |
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Heat of vaporization | 6.53 kJ/mol |
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Molar heat capacity | 20.85[4] J/(mol·K) |
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Vapor pressure
P (Pa) |
1 |
10 |
100 |
1 k |
10 k |
100 k |
at T (K) |
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47 |
53 |
61 |
71 |
87 |
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Oxidation states | 0 |
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Electronegativity | Pauling scale: no data |
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Ionization energies | - 1st: 1520.6 kJ/mol
- 2nd: 2665.8 kJ/mol
- 3rd: 3931 kJ/mol
- (more)
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Covalent radius | 106±10 pm |
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Van der Waals radius | 188 pm |
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Spectral lines of argon |
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Natural occurrence | primordial |
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Crystal structure | face-centered cubic (fcc) |
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Speed of sound | 323 m/s (gas, at 27 °C) |
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Thermal conductivity | 17.72×10−3 W/(m⋅K) |
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Magnetic ordering | diamagnetic[5] |
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CAS Number | 7440-37-1 |
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Discovery and first isolation | Lord Rayleigh and William Ramsay (1894) |
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Category: Argon | references |