Potassium

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Potassium
19K
Na

K

Rb
argonpotassiumcalcium
Appearance
sillery gray


Potassium pearls unner paraffin ile. The lairge pearl measures 0.5 cm. Albo: spectral lines o potassium
General properties
Name, seembol, nummer potassium, K, 19
Pronunciation /pɵˈtæsiəm/ po-TAS-ee-əm
Element category alkali metal
Group, period, block 1 (alkali metals), 4, s
Staundart atomic wicht 39.0983(1)
Electron confeeguration [Ar] 4s1
2, 8, 8, 1
Electron shells of potassium (2, 8, 8, 1)
History
Discovery Humphry Davy (1807)
First isolation Humphry Davy (1807)
Physical properties
Phase solid
Density (near r.t.) 0.862 g·cm−3
Liquid density at m.p. 0.828 g·cm−3
Meltin pynt 336.7 K, 63.5 °C, 146.3 °F
Boilin pynt 1032 K, 759 °C, 1398 °F
Creetical pynt 2223 K, 16[1] MPa
Heat o fusion 2.33 kJ·mol−1
Heat o vaporization 76.9 kJ·mol−1
Molar heat capacity 29.6 J·mol−1·K−1
Atomic properties
Oxidation states 1, −1
(strangly basic oxide)
Electronegativity 0.82 (Pauling scale)
Ionization energies
(more)
1st: 418.8 kJ·mol−1
2nt: 3052 kJ·mol−1
3rd: 4420 kJ·mol−1
Atomic radius 227 pm
Covalent radius 203±12 pm
Van der Waals radius 275 pm
Miscellanea
Crystal structure body-centered cubic
Potassium has a body-centered cubic crystal structure
Magnetic orderin paramagnetic[2]
Electrical resistivity (20 °C) 72 nΩ·m
Thermal conductivity 102.5 W·m−1·K−1
Thermal expansion (25 °C) 83.3 µm·m−1·K−1
Speed of sound (thin rod) (20 °C) 2000 m·s−1
Young's modulus 3.53 GPa
Shear modulus 1.3 GPa
Bulk modulus 3.1 GPa
Mohs hairdness 0.4
Brinell hairdness 0.363 MPa
CAS registry nummer 7440-09-7
Most stable isotopes
Main article: Isotopes o potassium
iso NA hauf-life DM DE (MeV) DP
39K 93.26% 39K is stable wi 20 neutrons
40K 0.012% 1.248(3)×109 y β 1.311 40Ca
ε 1.505 40Ar
β+ 1.505 40Ar
41K 6.73% 41K is stable wi 22 neutrons
· r

Potassium is a chemical element wi seembol K (frae Neo-Laitin kalium) an atomic nummer 19. Elemental potassium is a saft sillery-white alkali metal that oxidizes rapidly in air an is very reactive wi watter, generatin sufficient heat tae ignite the hydrogen emittit in the reaction an burnin wi a lilac flame. Naiturally occurrin potassium is componed o three isotopes, ane o which, 40K, is radioactive. Traces (0.012%) o this isotope is foond in aw potassium makin it the maist common radioactive element in the human body an in many biological materials, as well as in common biggin materials such as concrete.

References[eedit | eedit soorce]

  1. Haynes, William M., ed. (2011). CRC Handbook of Chemistry and Physics (92nd ed.). CRC Press. p. 4.122. ISBN 1439855110. 
  2. Magnetic susceptibility of the elements and inorganic compounds, in Lide, D. R., ed. (2005). CRC Handbook of Chemistry and Physics (86th ed.). Boca Raton (FL): CRC Press. ISBN 0-8493-0486-5.