Symbol K
Atomic Number 19
Atomic Mass 39.0983 amu
Discovered by Humphry Davy in 1807

Chemical Properties

Group 1 Melting point 63.5°C, 146.3°F, 336.7 K
Period 4 Boiling point 759°C, 1398°F, 1032 K
Block s Density (g cm−3) 0.89
Atomic number 19 Relative atomic mass 39.098
State at 20°C Solid Key isotopes 39K
Electron configuration [Ar] 4s1 CAS number 7440-09-7
ChemSpider ID 4575326 ChemSpider is a free chemical structure database

What is Potassium?

  • Potassium is the first element of the fourth period (row) in the periodic table.
  • The term potassium arises from a material called Potash.
  • The element has been in use for hundreds of years.
  • It is an alkali metal along with lithium, rubidium, sodium, cesium, and francium
  • It is a very active metal and never occurs free in nature and it always forms a compound with other elements.

Isotopes Of Potassium

Potassium usually has three isotopes, it goes by the name of potassium-39, 40 and 41. The potassium-40 is highly radioactive and can be found in rocks, plants, and animals. It is used to measure the age of objects. This isotope breaks down into an isotope of argon.

Uses Of Potassium

  • It can be used as a medium of heat exchange and are used in nuclear power plants because of this reason
  • People use the potassium salts as a constituent of fertilizer.
  • It is one of the essential nutrients of the human body
  • Potassium chloride is also used in injections.
  • Potash can be used to make glass and soap etc

Physical and Chemical Properties Of Potassium

  • It is soft and shiny metal which has a melting point 63 degrees and the boiling point as 770 degrees.
  • Potassium metal can float on water
  • It reacts with water violently and gives hydrogen which can actually catch fire and may explode
  • It can readily react with chlorine, fluorine, sulfur, nitrogen and phosphorous.
  • It has a green vapour and lavender cloured flame
  • It is ranked as the 7th most abundant element present in the earth’s crust.
  • The element is always traced in combination with other elements.
  • Once isolated, potassium turns into a malleable metal with a silver color profile.
  • Potassium reacts with water violently and gives off hydrogen gas

Certain Facts About Potassium

  • The symbol of Potassium (K) signifies the term Kalium.
  • It is an ancient term used to label the element and has its roots in the term “alkali.”
  • Like the other elements in the first column, potassium is an associate of the alkali group with cesium and sodium.
  • It was the first metal to get isolated by electrolysis

Practise This Question

On heating ammonium dichromate, the gas evolved is (IIT JEE,1999)