Potassium (K) is a chemical element in Group 1 (Ia) of the periodic table and part of the alkali metal group. It is indispensable for plant and animal life. The English chemist Sir Humphry Davy first isolated potassium in 1807 through the electrolysis of molten potassium hydroxide (KOH) using a voltaic battery. Key properties of potassium: * Atomic number: 19 * Atomic weight: 39.098 * Melting point: 63.28 °C (145.90 °F) * Good conductor of heat and electricity Potassium is the seventh most abundant element in the Earth's crust, making up 2.6% of its mass. It is found in minerals like muscovite and orthoclase feldspar, which are insoluble in water, making potassium difficult to extract. Most commercial potassium compounds are obtained through electrolysis from soluble potassium compounds.

Where is potassium found in nature?

Potassium, the seventh most abundant element in Earth's crust, constitutes 2.6 percent of its mass. It is found in various minerals like muscovite and orthoclase feldspar, which are common in igneous rocks, shale, and sediment. Potassium is also present in the Dead Sea, with an estimated concentration of 1.7 percent potassium chloride. Seawater also contains potassium. The waste liquors from certain saltworks can contain up to 40 grams per liter of potassium chloride and are utilized as a source of potassium.

What are some important uses of potassium?

Potassium is indispensable for both plants and animals. Its compounds have various important applications:

Why do living things need potassium?

Living things need potassium for several reasons: * Normal Function: Potassium is crucial for appropriate nerve and muscle responsiveness and maintaining heart rhythm. * Nutrient Balance: It helps balance nutrient intake and waste removal from cells. * Electrochemical Impulses: Potassium is also needed for transmitting electrochemical impulses in nerve and muscle fibers. * Photosynthesis: Plants require it for photosynthesis, enzyme activation, osmosis regulation, and growth. * Sodium-Potassium Pump: The sodium-potassium pump maintains the resting potential in neurons and is also vital for active transport, which transmits electrochemical impulses in nerve and muscle fibers. * Intracellular Fluid: Potassium is important for intracellular fluid pressure and balance. * Other: Potassium is also essential for enzyme activation and the metabolism of nitrogen compounds.

What does potassium look like and what are its main properties?

Potassium (K) is a chemical element in the alkali metal group. In its elemental form, potassium is a soft, silvery-white metal with a low melting point and is a good conductor of heat and electricity. Here are some of its key properties: Atomic number: 19 Atomic weight: 39.098 Melting point: 63.28 °C (145.90 °F) Boiling point: 760 °C (1,400 °F) Specific gravity: 0.862 (at 20 °C, or 68 °F) Oxidation states: +1, −1 (rare) Electron configuration: 2-8-8-1 or 1s22s22p63s23p64s1 Potassium is indispensable for both plant and animal life. The metal reacts vigorously with water, liberating hydrogen, which ignites and forms a solution of potassium hydroxide.

How does potassium react with water and why is this reaction important?

Potassium, an alkali metal, reacts violently with water, producing potassium hydroxide and hydrogen gas. The reaction is exothermic, generating heat, and the hydrogen gas can react with oxygen, further increasing the heat. [ M + H_2O \rightarrow MOH + 1/2 H_2 ] The rate of reaction depends on the metal surface exposed to the liquid; small droplets or thin films of the metal can cause an explosion. Potassium compounds, particularly potassium chloride (KCl), are essential in agriculture as fertilizers . They are also used to produce other potassium compounds, such as potassium hydroxide, which is used in making soaps and detergents.

potassium

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A periodic table element box for potassium shows atomic number 19, symbol K, atomic weight 39.0983, electron configuration [Ar]4s1, and name potassium. Icons indicate it is an alkali metal, solid at room temperature, body-centered cubic crystal structure, and has strongly basic higher-valence oxides. A key explains the symbols for alkali metals, solid state, body-centered cubic structure, and strong basicity.

Aerial view of the potash mine at Esterhazy, Saskatchewan, showing industrial buildings, storage facilities, and plumes of steam or smoke surrounded by snowy fields.

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Line graph showing the first ionization energies of the elements as a function of atomic number, with peaks at noble gases like helium, neon, argon, krypton, xenon, and radon, and labeled elements at key points.

Learn about the underground beds of potash deposits in Germany

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At a Glance

potassium summary

Quick Facts

Key People:: Sir Humphry Davy; Joseph-Louis Gay-Lussac

Related Topics:: chemical element; human nutrition; Are Bananas Radioactive?; potassium deficiency; potassium-40

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potassium

chemical element

Also known as: K, kalium

Written and fact-checked by

Britannica Editors

Last updated

Aug. 20, 2026 •History

Top Questions

What is potassium?
Potassium (K) is a chemical element in Group 1 (Ia) of the periodic table and part of the alkali metal group. It is indispensable for plant and animal life. The English chemist Sir Humphry Davy first isolated potassium in 1807 through the electrolysis of molten potassium hydroxide (KOH) using a voltaic battery.

Key properties of potassium:
* Atomic number: 19
* Atomic weight: 39.098
* Melting point: 63.28 °C (145.90 °F)
* Good conductor of heat and electricity

Potassium is the seventh most abundant element in the Earth's crust, making up 2.6% of its mass. It is found in minerals like muscovite and orthoclase feldspar, which are insoluble in water, making potassium difficult to extract. Most commercial potassium compounds are obtained through electrolysis from soluble potassium compounds.
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2. potassium
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Where is potassium found in nature?
Potassium, the seventh most abundant element in Earth's crust, constitutes 2.6 percent of its mass. It is found in various minerals like muscovite and orthoclase feldspar, which are common in igneous rocks, shale, and sediment.

Potassium is also present in the Dead Sea, with an estimated concentration of 1.7 percent potassium chloride. Seawater also contains potassium. The waste liquors from certain saltworks can contain up to 40 grams per liter of potassium chloride and are utilized as a source of potassium.
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2. potassium: Properties, occurrence, and uses
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What are some important uses of potassium?
Potassium is indispensable for both plants and animals. Its compounds have various important applications:
- Fertilizers Approximately 95% of commercially produced potassium compounds are utilized in agriculture as fertilizer. Potassium chloride is a naturally occurring salt that is also a raw material in the production of other potassium compounds.
- Industrial uses Potassium hydroxide is employed in making liquid soaps and detergents. Potassium nitrate is used in fireworks and explosives. Potassium chloride is used when welding aluminum.
- Dietary supplement Potassium iodide is added to table salt and animal feed to protect against iodine deficiency. Potassium chloride can be used as a salt substitute and is also added to animal feed to increase milk production in cows and goats.
- Medical Potassium is needed for proper function of the heart, muscles, kidneys, and nervous and digestive systems.
- Other Potassium superoxide is used in respiratory equipment as it produces oxygen and takes away carbon dioxide and water vapor.
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Why do living things need potassium?
Living things need potassium for several reasons:
* Normal Function: Potassium is crucial for appropriate nerve and muscle responsiveness and maintaining heart rhythm.
* Nutrient Balance: It helps balance nutrient intake and waste removal from cells.
* Electrochemical Impulses: Potassium is also needed for transmitting electrochemical impulses in nerve and muscle fibers.
* Photosynthesis: Plants require it for photosynthesis, enzyme activation, osmosis regulation, and growth.
* Sodium-Potassium Pump: The sodium-potassium pump maintains the resting potential in neurons and is also vital for active transport, which transmits electrochemical impulses in nerve and muscle fibers.
* Intracellular Fluid: Potassium is important for intracellular fluid pressure and balance.
* Other: Potassium is also essential for enzyme activation and the metabolism of nitrogen compounds.
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What does potassium look like and what are its main properties?
Potassium (K) is a chemical element in the alkali metal group. In its elemental form, potassium is a soft, silvery-white metal with a low melting point and is a good conductor of heat and electricity.

Here are some of its key properties:
- Atomic number: 19
- Atomic weight: 39.098
- Melting point: 63.28 °C (145.90 °F)
- Boiling point: 760 °C (1,400 °F)
- Specific gravity: 0.862 (at 20 °C, or 68 °F)
- Oxidation states: +1, −1 (rare)
- Electron configuration: 2-8-8-1 or 1s22s22p63s23p64s1
Potassium is indispensable for both plant and animal life. The metal reacts vigorously with water, liberating hydrogen, which ignites and forms a solution of potassium hydroxide.
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How does potassium react with water and why is this reaction important?
Potassium, an alkali metal, reacts violently with water, producing potassium hydroxide and hydrogen gas. The reaction is exothermic, generating heat, and the hydrogen gas can react with oxygen, further increasing the heat.

[
M + H_2O \rightarrow MOH + 1/2 H_2
]

The rate of reaction depends on the metal surface exposed to the liquid; small droplets or thin films of the metal can cause an explosion. Potassium compounds, particularly potassium chloride (KCl), are essential in agriculture as fertilizers. They are also used to produce other potassium compounds, such as potassium hydroxide, which is used in making soaps and detergents.
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1. potassium: Principal compounds and reactions with other elements
2. alkali metal: Reactions with water
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potassium (K), chemical element of Group 1 (Ia) of the periodic table, the alkali metal group, indispensable for both plant and animal life. Potassium was the first metal to be isolated by electrolysis, by the English chemist Sir Humphry Davy, when he obtained the element (1807) by decomposing molten potassium hydroxide (KOH) with a voltaic battery.

Element Properties
atomic number	19
atomic weight	39.098
melting point	63.28 °C (145.90 °F)
boiling point	760 °C (1,400 °F)
specific gravity	0.862 (at 20 °C, or 68 °F)
oxidation states	+1, −1 (rare)
electron configuration	2-8-8-1 or 1s²2s²2p⁶3s²3p⁶4s¹

Properties, occurrence, and uses

Potassium metal is soft and white with a silvery lustre, has a low melting point, and is a good conductor of heat and electricity. Potassium imparts a lavender colour to a flame, and its vapour is green. It is the seventh most abundant element in Earth’s crust, constituting 2.6 percent of its mass.

The potassium content of the Dead Sea is estimated at approximately 1.7 percent potassium chloride, and many other salty bodies of water are rich in potassium. The waste liquors from certain saltworks may contain up to 40 grams per litre of potassium chloride and are used as a source of potassium.

Most potassium is present in igneous rocks, shale, and sediment in minerals such as muscovite and orthoclase feldspar that are insoluble in water; this makes potassium difficult to obtain. As a result, most commercial potassium compounds (often loosely called potash) are obtained via electrolysis from soluble potassium compounds, such as carnallite (KMgCl₃∙6H₂O), sylvite (potassium chloride, KCl), polyhalite (K₂Ca₂Mg[SO₄]₄∙2H₂O), and langbeinite (K₂Mg₂[SO₄]₃), which are found in ancient lake beds and seabeds.

Potassium is produced by sodium reduction of molten potassium chloride, KCl, at 870 °C (1,600 °F). Molten KCl is continuously fed into a packed distillation column while sodium vapour is passed up through the column. By condensation of the more volatile potassium at the top of the distillation tower, the reaction Na + KCl → K + NaCl is forced to the right. Efforts to devise a scheme for commercial electrolytic production of potassium have been unsuccessful because there are few salt additives that can reduce the melting point of potassium chloride to temperatures where electrolysis is efficient.

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There is little commercial demand for potassium metal itself, and most of it is converted by direct combustion in dry air to potassium superoxide, KO₂, which is used in respiratory equipment because it liberates oxygen and removes carbon dioxide and water vapour. (The superoxide of potassium is a yellow solid consisting of K⁺and O₂⁻ ions. It also can be formed by oxidation of potassium amalgam with dry air or oxygen.) The metal is also used as an alloy with sodium as a liquid metallic heat-transfer medium. Potassium reacts very vigorously with water, liberating hydrogen (which ignites) and forming a solution of potassium hydroxide, KOH.

Sodium-potassium alloy (NaK) is used to a limited extent as a heat-transfer coolant in some fast-breeder nuclear reactors and experimentally in gas-turbine power plants. The alloy is also used as a catalyst or reducing agent in organic synthesis.

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In addition to the alloys of potassium with lithium and sodium, alloys with other alkali metals are known. Complete miscibility exists in the potassium-rubidium and potassium-cesium binary systems. The latter system forms an alloy melting at approximately −38 °C (−36 °F). Modification of the system by the addition of sodium results in a ternary eutectic melting at approximately −78 °C (−108 °F). The composition of this alloy is 3 percent sodium, 24 percent potassium, and 73 percent cesium. Potassium is essentially immiscible with all the alkaline-earth metals, as well as with zinc, aluminum, and cadmium.

Potassium (as K⁺) is required by all plants and animals. Plants need it for photosynthesis, regulation of osmosis and growth, and enzyme activation. Every animal has a closely maintained potassium level and a relatively fixed potassium-sodium ratio. Potassium is the primary inorganic cation within the living cell, and sodium is the most abundant cation in extracellular fluids. In higher animals, selective complexants for Na⁺ and K⁺ act at cell membranes to provide “active transport.” This active transport transmits electrochemical impulses in nerve and muscle fibres and in balancing the activity of nutrient intake and waste removal from cells. Too little or too much potassium in the body is fatal; however, potassium in the soil ensures the presence of this indispensable element in food.

The potassium content of plants varies considerably, though it is ordinarily in the range of 0.5–2 percent of the dry weight. In humans the ratio of potassium between the cell and plasma is approximately 27:1. The potassium content of muscle tissue is approximately 0.3 percent, whereas that of blood serum is about 0.01–0.02 percent. The dietary requirement for normal growth is approximately 3.3 grams (0.12 ounce) of potassium per day, but the ingestion of more than 20 grams (0.7 ounce) of potassium results in distinct physiological effects. Excess potassium is excreted in the urine, and a significant quantity may be lost during sweating.

Natural potassium consists of three isotopes: potassium-39 (93.26 percent), potassium-41 (6.73 percent), and radioactive potassium-40 (about 0.01 percent); several artificial isotopes have also been prepared. Potassium-39 is normally about 13.5 times more plentiful than potassium-41. The natural radioactivity of potassium is due to beta radiation from the potassium-40 isotope (10⁹ years half-life). The disintegration of potassium-40 is used in geological age calculations (see potassium-argon dating). Potassium easily loses the single 4s electron, so it normally has an oxidation state of +1 in its compounds, although compounds that contain the anion, K⁻, can also be made.