![Template:Infobox element/symbol-to-top-image/alt](https://upload.wikimedia.org/wikipedia/commons/thumb/a/a4/Potassium-2.jpg/220px-Potassium-2.jpg) Potassium pearls (in paraffin ile, ~5 mm ilk) |
Potassium |
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Pronunciation | (pə-TASS-ee-əm) |
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Appearance | sillery gray |
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Standard atomic weight Ar, std(K) | 7001390983000000000♠39.0983(1)[1] |
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Potassium in the periodic cairt |
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Atomic nummer (Z) | 19 |
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Group | group 1 (alkali metals) |
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Period | period 4 |
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Block | s-block |
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Element category | Alkali metal |
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Electron confeeguration | [Ar] 4s1 |
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Electrons per shell | 2, 8, 8, 1 |
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Pheesical properties |
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Phase at STP | solit |
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Meltin pynt | 336.7 K (63.5 °C, 146.3 °F) |
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Bylin pynt | 1032 K (759 °C, 1398 °F) |
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Density (near r.t.) | 0.862 g/cm3 |
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when liquid (at m.p.) | 0.828 g/cm3 |
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Creetical pynt | 2223 K, 16[2] MPa |
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Heat o fusion | 2.33 kJ/mol |
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Heat o vapourisation | 76.9 kJ/mol |
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Molar heat capacity | 29.6 J/(mol·K) |
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Atomic properties |
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Oxidation states | −1, +1 strangly basic |
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Electronegativity | Pauling scale: 0.82 |
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Ionisation energies | |
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Atomic radius | empirical: 227 pm |
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Covalent radius | 203±12 pm |
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Van der Waals radius | 275 pm |
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Colour lines in a spectral rangeSpectral lines o potassium |
Ither properties |
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Naitural occurrence | primordial |
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Creestal structur | body-centred cubic (bcc) |
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Speed o soond thin rod | 2000 m/s (at 20 °C) |
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Thermal expansion | 83.3 µm/(m·K) (at 25 °C) |
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Thermal conductivity | 102.5 W/(m·K) |
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Electrical resistivity | 72 n Ω·m (at 20 °C) |
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Magnetic orderin | paramagnetic[3] |
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Young's modulus | 3.53 GPa |
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Shear modulus | 1.3 GPa |
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Bulk modulus | 3.1 GPa |
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Mohs haurdness | 0.4 |
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Brinell haurdness | 0.363 MPa |
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CAS Nummer | 7440-09-7 |
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History |
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Diskivery | Humphry Davy (1807) |
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First isolation | Humphry Davy (1807) |
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Main isotopes o potassium |
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Isotope
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Abundance
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Hauf-life (t1/2)
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Decay mode
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Product
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39K
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93.26%
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stable
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40K
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0.012%
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1.248(3)×109 y
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β−
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40Ca
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ε
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40Ar
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β+
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40Ar
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41K
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6.73%
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stable
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| references |