WebElements Periodic Table » Potassium » the essentials (2024)

▸▸

  • 🇬🇧Potassium
  • 🇺🇦Калій
  • 🇨🇳鉀
  • 🇳🇱Kalium
  • 🇫🇷Potassium
  • 🇩🇪Kalium
  • 🇮🇱אשלגן
  • 🇮🇹Potassio
  • 🇯🇵カリウム
  • 🇵🇹Potássio
  • 🇪🇸Potasio
  • 🇸🇪Kalium
  • 🇷🇺Калий
  • ▸▸ K Essentials
  • Physical properties
  • Electron shell data
  • Atom sizes
  • Electronegativity
  • Isotopes and NMR
  • Crystal structure
  • Thermochemistry
  • History
  • Uses
  • Geology
  • Biology
  • Binary compounds
  • Compound properties
  • Element reactions
  • List all K properties
  • Name: potassium
  • Symbol: K
  • Atomic number: 19
  • Relative atomic mass (Ar): 39.0983 (1)
  • Standard state: solid at 298 K
  • Appearance: silvery white
  • Classification: Metallic
  • Group in periodic table: 1
  • Group name: Alkali metal
  • Period in periodic table: 4
  • Block in periodic table: s
  • Shell structure: 2.8.8.1
  • CAS Registry: 7440-09-7

Potassium atoms have 19 electrons and the shell structure is2.8.8.1. The ground state electronic configuration of neutral potassium is[Ar].4s1 and the term symbol of potassium is2S1/2.

Potassium: description

Potassium is a metal and is the seventh most abundant and makes up about 1.5 % by weight of the earth's crust. Potassium is an essential constituent for plant growth and it is found in most soils. It is also a vital element in the human diet.

Potassium is never found free in nature, but is obtained by electrolysis of the chloride or hydroxide, much in the same manner as prepared by Davy. It is one of the most reactive and electropositive of metals and, apart from lithium, it is the least dense known metal. It is soft and easily cut with a knife. It is silvery in appearance immediately after a fresh surface is exposed.

It oxidises very rapidly in air and must be stored under argon or under a suitable mineral oil. As do all the other metals of the alkali group, it decomposes in water with the evolution of hydrogen. It usually catches fire during the reaction with water. Potassium and its salts impart a lilac colour to flames.

WebElements Periodic Table » Potassium » the essentials (1)
The picture above shows the colour arising from a burning mixture of potassium chlorate (KClO3) and sucrose (only to be demonstrated by a professionally qualified chemist).

WebElements Periodic Table » Potassium » the essentials (2)
The chemistry of potassium is dominated by electron loss to form K+. Cartoon by Nick D Kim ([Science and Ink], used by permission).

Potassium: physical properties

  • Density of solid: 856kg m-3
  • Molar volume: 45.94cm3
  • Thermal conductivity: 100Wm‑1K‑1

More physical properties...

Potassium: heat properties

  • Melting point: 336.53 [63.38°C (146.08°F)]K
  • Boiling point: 1032 [759°C (1398°F)]K
  • Enthalpy of fusion: 20.5kJ mol-1

More thermochemical properties...

Potassium: atom sizes

  • Atomic radius (empirical): 220pm
  • Molecular single bond covalent radius: 196 (coordination number 1)ppm
  • van der Waals radius: 273ppm

More atomc size properties...

Potassium: electronegativities

  • Pauling electronegativity: 0.82 (Pauling units)
  • Allred Rochow electronegativity: 0.91 (Pauling units)
  • Mulliken-Jaffe electronegativity: 0.73 (s orbital)

More electronegativity properties...

Potassium: orbital properties

  • First ionisation energy: 418.81kJmol‑1
  • Second ionisation energy: 3051.35kJmol‑1
  • Third ionisation energy: 4419.3kJmol‑1

More orbital properties...

Potassium: abundances

  • Universe: 3000ppb by weight
  • Crustal rocks: 15000000ppb by weight
  • Human: 2000000ppb by weight

More geological data...

Potassium: crystal structure

WebElements Periodic Table » Potassium » the essentials (21)

More crystallographic data...

Potassium: biological data

  • Human abundance by weight: 2000000ppb by weight

Potassium salts are essential for both animals and plants. The potassium cation (K+) is the major cation in intracellular (inside cells) fluids (sodium is the main extracellular cation). It is essential for nerve and heart function. A normal diet containing reasonable amounts of vegetables contains all the potassium necessary.

More biological data...

Potassium: uses

Uses...

Potassium: reactions

Reactions of potassium as the element with air, water, halogens, acids, and bases where known.

View reactions of potassium...

Potassium: binary compounds

Binary compounds with halogens (known as halides), oxygen (known as oxides), hydrogen (known as hydrides), and other compounds of potassium where known.

View binary compounds...

Potassium: compound properties

Bond strengths; lattice energies of potassium halides, hydrides, oxides (where known); and reduction potentials where known.

View compound properties...

Potassium: history

Potassium was discovered by Sir Humphrey Davy in 1807 at England. Origin of name: from the English word "potash" (pot ashes) and the Arabic word "qali" meaning alkali (the origin of the symbol K comes from the Latin word "kalium").

More history...

Potassium: isotopes

WebElements Periodic Table » Potassium » the essentials (23)

Although Potassium only has two stable isotopes (K-39 and K-41), the long-lived radioisotope K-40 is often also regarded as a stable isotope. Potassium isotopes, mainly K-40 and K-41, are used to study the impact of potassium on the growth of plants and of the human cardiovascular system.

More isotope and NMR data...

Potassium: isolation

Isolation: potassium would not normally be made in the laboratory as it is so readily available commercially. All syntheses require an electrolytic step as it is so difficult to add an electron to the poorly electronegative potassium ion K+.

Potassium is not made by the same method as sodium as might have been expected. This is because the potassium metal, once formed by electrolysis of liquid potassium chloride (KCl), is too soluble in the molten salt.

cathode: K+(l) + e- → K (l)

anode: Cl-(l) → 1/2Cl2 (g) + e-

Instead, it is made by the reaction of metallic sodium with molten potassium chloride at 850°C.

Na + KCl ⇌ K + NaCl

This is an equilibrium reaction and under these conditions the potassium is highly volatile and removed from the system in a form relatively free from sodium impurities, allowing the reaction to proceed.

WebElements Periodic Table » Potassium » the essentials (2024)

FAQs

What is the periodic table of elements for potassium? ›

Potassium is a chemical element; it has symbol K (from Neo-Latin kalium) and atomic number 19. It is a silvery white metal that is soft enough to easily cut with a knife. Potassium metal reacts rapidly with atmospheric oxygen to form flaky white potassium peroxide in only seconds of exposure.

What elements does potassium like to bond with? ›

Potassium metal reacts vigorously with all the halogens to form potassium halides. So, it reacts with fluorine, F2, chlorine, Cl2, bromine, I2, and iodine, I2, to form respectively potassium(I) bromide, KF, potassium(I) chloride, KCl, potassium(I) bromide, KBr, and potassium(I) iodide, KI.

Why is K the symbol of potassium? ›

The name is derived from the english word potash. The chemical symbol K comes from kalium, the Mediaeval Latin for potash, which may have derived from the arabic word qali, meaning alkali. Potassium is a soft, silvery-white metal, member of the alkali group of the periodic chart.

What is the reactivity of potassium? ›

Just like other alkali metals, potassium is very reactive. It can react with water violently to produce hydrogen (H2) gas. The excessive heat generated by this reaction, together with the H2 as a product, can be explosive. Potassium can also react with air and form oxide layers.

What is the formula for potassium? ›

It is found that potassium occurs only in ionic salts in nature. - The chemical formula of potassium is K. - Potassium metal reacts rapidly with atmospheric oxygen, and forms white potassium peroxide . Its name was derived from potash, which means the ashes of plants.

How many protons are in potassium? ›

This tells us that in an atom of K there are 19 protons and 19 electrons.

What element reacts violently with potassium? ›

Hence chlorine and potassium will react more violently.

What does potassium not react with? ›

Potassium is not reactive with benzene, although heavier alkali metals such as cesium react to give organometallic products.

What element is closest to potassium? ›

cesium is chemically similar to potassium since it is in the same group. Cesium is also an alkali metal, can be found in the first column of the periodic table, and can lose one electron to form a cation with a 1+ charge. Moreover, it has one valence electron found on the s orbital.

Why is potassium good for the body? ›

Potassium has many important functions: It allows the nerves to respond to stimulation and muscles to contract (tighten), including those in the heart. It reduces the effect of sodium (present in table salt) on blood pressure. It helps move nutrients into cells, and waste products out of cells.

Why is potassium unique? ›

Potassium was the first metal to be isolated using electrolysis. Potassium compounds emit a lilac or violet flame color when burned. It burns in water, just like sodium. The difference is that sodium burns with a yellow flame and is more likely to shatter and explode!

What is another name for potassium? ›

Whilst Davy named his new metal potassium after the potash, Berzelius, the Swedish chemist who invented the international system of chemical symbols now used by chemists the world over, preferred the name kalium for the metal, better reflecting its true origins, he thought.

What element ignites in water? ›

Answer and Explanation: The chemical elements that explode when water touches them are lithium, sodium, potassium, rubidium, and cesium. All five of these elements are classified as alkali metals and are found in the first column of the periodic table of elements.

Why does potassium catch fire in water? ›

Potassium reacts violently on contact with powerful oxidizers and water. Do not grind potassium or heat it. Upon contact with water, acids or alcohols, potassium produces an exothermic reaction involving release of flammable hydrogen gas. Oxidized potassium may explode upon handling.

Potassium (K) - Chemical properties, Health and ...Lenntechhttps://www.lenntech.com ›

The chemical symbol K comes from kalium, the Mediaeval Latin for potash, which may have derived from the arabic word qali, meaning alkali. Potassium is a soft, ...
What do you think of when you look at element number 19 on the periodic table? As a chemist, I suppose my head should be filled with images of chemically relate...
Potassium is an alkali metal. It makes up 2.4% of the Earth's mass. Potassium can be found naturally as mineral (usually igneous) and salt compounds. Despit...

What is the atomic mass for potassium? ›

Potassium is the first element of the fourth period (row) in the periodic table. The atomic mass of potassium is 39.098 atomic mass units.

What is the structure of potassium? ›

The nucleus consists of 19 protons (red) and 21 neutrons (blue). 19 electrons (green) bind to the nucleus, with a single, relatively unstable electron in the outer shell (ring). The stability of an element's outer electrons determines its chemical and physical properties.

Is potassium a metal or nonmetal? ›

Hence, potassium is a metal.

What is f in periodic table? ›

Fluorine is a chemical element with symbol F and atomic number 9. Classified as a halogen, Fluorine is a gas at room temperature.

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