A krypton-filled discharge tube glowing white |
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Pronunciation | (KRIP-ton) |
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Appearance | colorless gas, exhibiting a whitish glow in an electric field |
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| 83.798(2)[1] |
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Atomic number (Z) | 36 |
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Group | group 18 (noble gases) |
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Period | period 4 |
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Block | p-block |
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Electron configuration | [Ar] 3d10 4s2 4p6 |
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Electrons per shell | 2, 8, 18, 8 |
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Phase at STP | gas |
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Melting point | 115.78 K (−157.37 °C, −251.27 °F) |
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Boiling point | 119.93 K (−153.415 °C, −244.147 °F) |
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Density (at STP) | 3.749 g/L |
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when liquid (at b.p.) | 2.413 g/cm3[2] |
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Triple point | 115.775 K, 73.53 kPa[3][4] |
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Critical point | 209.48 K, 5.525 MPa[4] |
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Heat of fusion | 1.64 kJ/mol |
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Heat of vaporization | 9.08 kJ/mol |
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Molar heat capacity | 20.95[5] J/(mol·K) |
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Vapor pressure
P (Pa) |
1 |
10 |
100 |
1 k |
10 k |
100 k |
at T (K) |
59 |
65 |
74 |
84 |
99 |
120 |
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Oxidation states | 0, +1, +2 (rarely more than 0; oxide is unknown) |
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Electronegativity | Pauling scale: 3.00 |
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Ionization energies | - 1st: 1350.8 kJ/mol
- 2nd: 2350.4 kJ/mol
- 3rd: 3565 kJ/mol
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Covalent radius | 116±4 pm |
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Van der Waals radius | 202 pm |
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Spectral lines of krypton |
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Natural occurrence | primordial |
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Crystal structure | face-centered cubic (fcc) |
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Speed of sound | (gas, 20 °C) 221 m·s−1 (liquid) 1120 m/s |
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Thermal conductivity | 9.43×10−3 W/(m⋅K) |
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Magnetic ordering | diamagnetic[6] |
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Molar magnetic susceptibility | −28.8×10−6 cm3/mol (298 K)[7] |
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CAS Number | 7439-90-9 |
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Discovery and first isolation | William Ramsay and Morris Travers (1898) |
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Main isotopes[8] |
Decay |
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abundance |
half-life (t1/2) |
mode |
product |
78Kr |
0.360% |
9.2×1021 y[9] |
εε |
78Se |
79Kr |
synth |
35 h |
ε |
79Br |
β+ |
79Br |
γ |
– |
80Kr |
2.29% |
stable |
81Kr |
trace |
2.3×105 y |
ε |
81Br |
81mKr |
|
13.10 s |
IT |
81Kr |
ε |
81Br |
82Kr |
11.6% |
stable |
83Kr |
11.5% |
stable |
84Kr |
57.0% |
stable |
85Kr |
synth |
11 y |
β− |
85Rb |
86Kr |
17.3% |
stable |
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Category: Krypton | references |