Template:Infobox potassium
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19 argon ← potassium → calcium Na ↑ K ↓ Rb Periodic table - Extended periodic table
General
Name, symbol, number	potassium, K, 19
Chemical series	alkali metals
Group, period, block	1, 4, s
Appearance	silvery white
Standard atomic weight	39.0983(1) g·mol−1
Electron configuration	Ar 4s1
Electrons per shell	2, 8, 8, 1
Physical properties
Phase	solid
Density (near r.t.)	0.89 g·cm−3
Liquid density at m.p.	0.828 g·cm−3
Melting point	336.53 K (63.38 °C, 146.08 °F)
Boiling point	1032 K (759 °C, 1398 °F)
Triple point	336.35 K (63°C),  kPa
Atomic properties
Crystal structure	cubic body centered
Oxidation states	1 (strongly basic oxide)
Electronegativity	0.82 (Pauling scale)
Ionization energies (more)	1st: 418.8 kJ·mol−1
	2nd: 3052 kJ·mol−1
	3rd: 4420 kJ·mol−1
Atomic radius	220 pm
Atomic radius (calc.)	243 pm
Covalent radius	196 pm
Van der Waals radius	275 pm
Miscellaneous
Magnetic ordering	paramagnetic
Thermal conductivity	(300 K) 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
Young's modulus	3.53 GPa
Shear modulus	1.3 GPa
Bulk modulus	3.1 GPa
Mohs hardness	0.4
Brinell hardness	0.363 MPa
CAS registry number	7440-09-7
Selected isotopes
Main article: Isotopes of potassium iso NA half-life DM DE (MeV) DP 39K 93.26% 39K is stable with 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 with 22 neutrons
References
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