POTASSIUM

DISCOVERED

Discovery date : 1807

Discovered by: Humphry Davy

Origin of the name: The name is derived from the English word 'potash'.

Allotropes :






~>POTASSIUM is a chemical element with symbol K and atomic number 19. It was first isolated from potash, the ashes of plants, from which its name derives. In the periodic table, potassium is one of the alkali metals.


FACT BOX
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 39 K
Electron configuration [Ar] 4s1 CAS number 7440-09-7
ChemSpider ID 4575326 ChemSpider is a free chemical structure database

ELEMENTS and PERIODIC TABLE HISTORY

Potassium salts in the form of saltpetre (potassium nitrate, KNO3), alum (potassium aluminium sulfate, KAl(SO4)2), and potash (potassium carbonate, K2CO3) have been known for centuries. They were used in gunpowder, dyeing, and soap making. They were scraped from the walls of latrines, manufactured from clay and sulfuric acid, and collected as wood ash respectively. Reducing them to the element defeated the early chemists and potassium was classed as an ‘earth’ by Antoine Lavoisier. Then in 1807, Humphry Davy exposed moist potash to an electric current and observed the formation of metallic globules of a new metal, potassium. He noted that when they were dropped into water they skimmed around on the surface, burning with a lavender-coloured flame.