Template:Infobox potassium

argon ← potassium → calcium Na ↑ K ↓ Rb 19K Periodic table
Appearance
silvery gray Potassium pearls under paraffin oil. The large pearl measures 0.5 cm. Below: spectral lines of potassium
General properties
Name, symbol, number	potassium, K, 19
Pronunciation	/pɵˈtæsiəm/ po-tas-ee-əm
Element category	alkali metal
Group, period, block	1, 4, s
Standard atomic weight	39.0983(1)
Electron configuration	[Ar] 4s1
Electrons per shell	2, 8, 8, 1 (Image)
Physical properties
Phase	solid
Density (near r.t.)	0.862 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
Heat of fusion	2.33 kJ·mol−1
Heat of vaporization	76.9 kJ·mol−1
Molar heat capacity	29.6 J·mol−1·K−1
Atomic properties
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	227 pm
Covalent radius	203±12 pm
Van der Waals radius	275 pm
Miscellanea
Crystal structure	body-centered cubic
Magnetic ordering	paramagnetic
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 hardness	0.4
Brinell hardness	0.363 MPa
CAS registry number	7440-09-7
Most stable 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