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Pronunciation | |
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Appearance | silvery white metallic; with a pale yellow tint[1] |
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| 87.62(1)[2] |
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Atomic number (Z) | 38 |
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Group | group 2 (alkaline earth metals) |
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Period | period 5 |
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Block | s-block |
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Electron configuration | [Kr] 5s2 |
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Electrons per shell | 2, 8, 18, 8, 2[3] |
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Phase at STP | solid |
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Melting point | 1050 K (777 °C, 1431 °F) |
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Boiling point | 1650 K (1377 °C, 2511 °F) |
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Density (near r.t.) | 2.64 g/cm3 |
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when liquid (at m.p.) | 2.375 g/cm3 |
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Heat of fusion | 7.43 kJ/mol |
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Heat of vaporization | 141 kJ/mol |
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Molar heat capacity | 26.4 J/(mol·K) |
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Vapor pressure
P (Pa) |
1 |
10 |
100 |
1 k |
10 k |
100 k |
at T (K) |
796 |
882 |
990 |
1139 |
1345 |
1646 |
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Oxidation states | +1,[4] +2 (a strongly basic oxide) |
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Electronegativity | Pauling scale: 0.95 |
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Ionization energies | - 1st: 549.5 kJ/mol
- 2nd: 1064.2 kJ/mol
- 3rd: 4138 kJ/mol
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Atomic radius | empirical: 215 pm |
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Covalent radius | 195±10 pm |
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Van der Waals radius | 249 pm |
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Spectral lines of strontium |
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Natural occurrence | primordial |
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Crystal structure | face-centered cubic (fcc) |
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Thermal expansion | 22.5 µm/(m⋅K) (at 25 °C) |
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Thermal conductivity | 35.4 W/(m⋅K) |
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Electrical resistivity | 132 nΩ⋅m (at 20 °C) |
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Magnetic ordering | paramagnetic |
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Molar magnetic susceptibility | −92.0×10−6 cm3/mol (298 K)[5] |
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Young's modulus | 15.7 GPa |
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Shear modulus | 6.03 GPa |
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Poisson ratio | 0.28 |
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Mohs hardness | 1.5 |
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CAS Number | 7440-24-6 |
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Naming | after the mineral strontianite, itself named after Strontian, Scotland |
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Discovery | William Cruickshank (1787) |
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First isolation | Humphry Davy (1808) |
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Main isotopes[6] |
Decay |
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abundance |
half-life (t1/2) |
mode |
product |
82Sr |
synth |
25.36 d |
ε |
82Rb |
83Sr |
synth |
1.35 d |
ε |
83Rb |
β+ |
83Rb |
γ |
– |
84Sr |
0.56% |
stable |
85Sr |
synth |
64.84 d |
ε |
85Rb |
γ |
– |
86Sr |
9.86% |
stable |
87Sr |
7% |
stable |
88Sr |
82.6% |
stable |
89Sr |
synth |
50.52 d |
β− |
89Y |
90Sr |
trace |
28.90 y |
β− |
90Y |
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Category: Strontium | references |