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Thorium |
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Pronunciation | (THOR-ee-əm) |
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Appearance | sillery, eften wi black tarnish |
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Standard atomic weight Ar, std(Th) | 7002232037700000000♠232.0377(4)[1] |
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Thorium in the periodic cairt |
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Atomic nummer (Z) | 90 |
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Group | group n/a |
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Period | period 7 |
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Block | f-block |
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Element category | Actinide |
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Electron confeeguration | [Rn] 6d2 7s2 |
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Electrons per shell | 2, 8, 18, 32, 18, 10, 2 |
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Pheesical properties |
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Phase at STP | solit |
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Meltin pynt | 2115 K (1842 °C, 3348 °F) |
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Bylin pynt | 5061 K (4788 °C, 8650 °F) |
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Density (near r.t.) | 11.7 g/cm3 |
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Heat o fusion | 13.81 kJ/mol |
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Heat o vapourisation | 514 kJ/mol |
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Molar heat capacity | 26.230 J/(mol·K) |
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Vapour pressur
P (Pa) |
1 |
10 |
100 |
1 k |
10 k |
100 k |
at T (K) |
2633 |
2907 |
3248 |
3683 |
4259 |
5055 |
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Atomic properties |
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Oxidation states | +1, +2, +3, +4 waikly basic |
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Electronegativity | Pauling scale: 1.3 |
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Atomic radius | empirical: 179 pm |
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Covalent radius | 206±6 pm |
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Spectral lines o thorium |
Ither properties |
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Naitural occurrence | primordial |
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Creestal structur | face-centred cubic (fcc) |
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Speed o soond thin rod | 2490 m/s (at 20 °C) |
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Thermal expansion | 11.0 µm/(m·K) (at 25 °C) |
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Thermal conductivity | 54.0 W/(m·K) |
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Electrical resistivity | 147 n Ω·m (at 0 °C) |
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Magnetic orderin | paramagnetic[2] |
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Young's modulus | 79 GPa |
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Shear modulus | 31 GPa |
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Bulk modulus | 54 GPa |
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Poisson ratio | 0.27 |
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Mohs haurdness | 3.0 |
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Vickers haurdness | 350 MPa |
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Brinell haurdness | 400 MPa |
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CAS Nummer | 7440-29-1 |
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History |
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Diskivery | Jöns Jakob Berzelius (1829) |
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Main isotopes o thorium |
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Isotope |
Abundance |
Hauf-life (t1/2) |
Decay mode |
Product |
228Th |
trace |
1.9116 y |
α |
224Ra |
229Th |
trace |
7340 y |
α |
225Ra |
230Th |
trace |
75380 y |
α |
226Ra |
231Th |
trace |
25.5 h |
β− |
231Pa |
232Th |
100% |
1.405×1010 y |
α |
228Ra |
234Th |
trace |
24.1 d |
β− |
234Pa |
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| references |