Periodic Table ~ potassium ~ Element ~ CAS 7440-09-7

potassium

Name	potassium
Symbol	K
Atomic Weight	39.0983
Atomic Number	19
CAS ID	7440-09-7
Group Number	1
Group Name	Alkali Metal
Period Number	4
Origin of Name	English, potash; Latin kalium.
Year Discovered	1807
Discovery Credits	Sir Humphry Davy at London, UK.
Class	Metallic
Color	Silvery White
Standard State	Solid at 77 F & 298 K
Description	Soft white metal, silvery when cut but reacts rapidly with oxygen and vigorously with water. Metal obtained from NaCl + KCl at 1100 K. Used in fertilizers, chemicals, and glass. Diagnostic tests: In solution, a potassium will give a violet flame test color. This flame test will be contaminated with the colors of the other alkaline elements which are present in the sample. The test is best observed through a blue filter to suppress the yellow sodium flame.