Infobox pòtásíọ̀mù

Potassium, ₁₉K

Potassium pearls (in paraffin oil, ~5 mm each)
Potassium
Pípè	/pəˈtæsiəm/ ​(pə-TAS-ee-əm)
Ìhànsójú	silvery gray
Ìwúwo átọ̀mù Ar, std(K)	39.0983(1)
Potassium ní orí tábìlì àyè
Hydrogen Helium Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson Na ↑ K ↓ Rb argon ← potassium → calcium
Nọ́mbà átọ̀mù (Z)	19
Ẹgbẹ́	group 1: H and alkali metals
Àyè	àyè 4
Àdìpọ̀	Àdìpọ̀-s
Ẹ̀ka ẹ́límẹ́ntì	Alkali metal
Ìtò ẹ̀lẹ́ktrọ́nù	[Ar] 4s1
Iye ẹ̀lẹ́ktrọ́nù lórí ìpele kọ̀ọ̀kan	2, 8, 8, 1
Àwọn ohun ìní ara
Ìfarahàn at STP	solid
Ìgbà ìyọ́	336.7 K ​(63.5 °C, ​146.3 °F)
Ígbà ìhó	1032 K ​(759 °C, ​1398 °F)
Kíki (near r.t.)	0.862 g/cm3
when liquid (at m.p.)	0.828 g/cm3
Critical point	2223 K, 16 MPa
Heat of fusion	2.33 kJ/mol
Heat of	76.9 kJ/mol
Molar heat capacity	29.6 J/(mol·K)
Atomic properties
Oxidation states	−1, +1 Àdàkọ:Infobox element/symbol-to-oxidation-state/comment
Electronegativity	Pauling scale: 0.82
energies	(more)
Atomic radius	empirical: 227 pm
Covalent radius	203±12 pm
Van der Waals radius	275 pm
Color lines in a spectral range Spectral lines of potassium
Other properties
Natural occurrence	primordial
Crystal structure	​(bcc)
Speed of sound thin rod	2000 m/s (at 20 °C)
Thermal expansion	83.3 µm/(m·K) (at 25 °C)
Thermal conductivity	102.5 W/(m·K)
Electrical resistivity	72 n Ω·m (at 20 °C)
Magnetic ordering	paramagnetic
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 Number	7440-09-7
History
Discovery	Humphry Davy (1807)
First isolation	Humphry Davy (1807)
Main isotopes of potassium
Iso­tope Abun­dance Half-life (t1/2) Decay mode Pro­duct 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