Potassium

Potassium is a chemical element wi seembol K (derived frae Neo-Latin, kalium) an atomic nummer 19. It wis first isolate frae potash, the ess o plants, frae whilk its name derives. In the periodic cairt, potassium is ane o the alkali metals. Aw o the alkali metals hae a single valence electron in the ooter electron shell, whilk is easy remuived tae creaut an ion wi a positive chairge – a cation, whilk combines wi anions tae form sauts. Potassium in naitur occurs anly in ionic sauts. Elemental potassium is a saft sillery-white alkali metal that oxidizes rapidly in air an reacts vigorously wi watter, generatin sufficient heat tae ignite hydrogen emittit in the reaction an burnin wi a lilac-colored flame. It is foond dissolved in sea watter (which is 0.04% potassium bi wecht^[4][5]), an is pairt o mony meenerals.

Potassium, ₁₉K

Potassium pearls (in paraffin ile, ~5 mm ilk)
Potassium
Pronunciation	/pəˈtæsiəm/ ​(pə-TASS-ee-əm)
Appearance	sillery gray
Standard atomic weight Ar, std(K)	7001390983000000000♠39.0983(1)[1]
Potassium in the periodic cairt
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 Airn Cobalt Nickel Capper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Siller (element) 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 Gowd Mercur (element) Thallium Leid (element) 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 Ununtrium Flerovium Ununpentium Livermorium Ununseptium Ununoctium Na ↑ K ↓ Rb argon ← potassium → calcium
Atomic nummer (Z)	19
Group	group 1 (alkali metals)
Period	period 4
Block	s-block
Element category	Alkali metal
Electron confeeguration	[Ar] 4s1
Electrons per shell	2, 8, 8, 1
Pheesical properties
Phase at STP	solit
Meltin pynt	336.7 K ​(63.5 °C, ​146.3 °F)
Bylin pynt	1032 K ​(759 °C, ​1398 °F)
Density (near r.t.)	0.862 g/cm3
when liquid (at m.p.)	0.828 g/cm3
Creetical pynt	2223 K, 16[2] MPa
Heat o fusion	2.33 kJ/mol
Heat o vapourisation	76.9 kJ/mol
Molar heat capacity	29.6 J/(mol·K)
Atomic properties
Oxidation states	−1, +1 strangly basic
Electronegativity	Pauling scale: 0.82
Ionisation energies	(more)
Atomic radius	empirical: 227 pm
Covalent radius	203±12 pm
Van der Waals radius	275 pm
Colour lines in a spectral range Spectral lines o potassium
Ither properties
Naitural occurrence	primordial
Creestal structur	​body-centred cubic (bcc)
Speed o soond 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 orderin	paramagnetic[3]
Young's modulus	3.53 GPa
Shear modulus	1.3 GPa
Bulk modulus	3.1 GPa
Mohs haurdness	0.4
Brinell haurdness	0.363 MPa
CAS Nummer	7440-09-7
History
Diskivery	Humphry Davy (1807)
First isolation	Humphry Davy (1807)
Main isotopes o potassium
Iso­tope Abun­dance Hauf-life (t1/2) Decay mode Pro­duct 39K 93.26% stable 40K 0.012% 1.248(3)×109 y β− 40Ca ε 40Ar β+ 40Ar 41K 6.73% stable
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Naiturally occurrin potassium is componed o three isotopes, o whilk ⁴⁰
K is radioactive. Traces o ⁴⁰
K are foond in aw potassium, an it is the maist common radioisotope in the human bouk.

Potassium is chemically gey seemilar tae sodium, the previous element in group 1 o the periodic table. Thay hae a seemilar first ionisation energy, whilk allous for ilka atom tae gie up its sole outer electron. That thay are different elements that combine wi the same anions tae mak seemilar salts wis suspected in 1702,^[6] an wis proven in 1807 uisin electrolysis.

Maist industrial applications o potassium exploits the heich solubility in watter o potassium compoonds, sic as potassium saips. Hivy crop production rapidly depletes the sile o potassium, an this can be remedied wi agricultural fertilizers containin potassium, accoontin for 95% o global potassium chemical production.^[7]

Potassium ions is necessar for the function o aw livin cells. The transfer o potassium ions throu nerve cell membranes is necessar for normal nerve transmission; potassium depletion can result in numerous abnormalities, includin an abnormal hert rhythm an various electrocardiographic (ECG) abnormalities. Fresh fruits an vegetables is guid dietar soorces o potassium. The body responds tae the influx o dietar potassium, whilk raises serum potassium levels, wi a shift o potassium frae ootside tae inside cells an an increase in potassium excretion bi the neers.