Home

Home
Common Compounds
Exam Guide
FAQ
Features
Glossary
Construction Kits
Companion Notes
Just Ask Antoine!
Simulations
Slide Index
Toolbox
Tutorial Index

FAQ
Introduction
Measurement
Matter
Atoms & ions
Compounds
Chemical change
The mole
Gases
Energy & change
The quantum theory
Electrons in atoms
The periodic table
Chemical bonds
Solids
Liquids
Solutions
Acids & bases
Redox reactions
Reaction rates
Organic chemistry
Everyday chemistry
Inorganic chemistry
Environmental chemistry
Laboratory
History of chemistry
Miscellaneous


Home :FAQ :History of chemistryPrint | Comment
Previous Question Next Question

Who discovered potassium and sodium?


Vocabulary
alkali metal*
electrolysis*
hydroxide*
reduction*
Alkali metals are so reactive that they never occur in uncombined form in nature. Many metals can be isolated from their minerals by reduction with carbon or hydrogen, but alkali metal ions are extremely difficult to reduce. A more powerful technology for metal reduction was needed before alkali metals could be isolated in pure elemental form.

Sir Humphry Davy believed that chemical union was electrical in nature- and so, a strong electric current might be able to overcome the forces binding compounds together, and lead to the isolation of new elements. In 1807 he tested this hypothesis on caustic potash (potassium hydroxide, KOH) and caustic soda (sodium hydroxide, NaOH), which had previously been suspected to be oxides of unknown metals.

Davy fired a small piece of KOH in a furnace and placed it on a platinum plate. He connected the plate to the negative terminal of an enormous battery made of 250 stacked cells made of 6" x 4" copper and zinc plates. The positive terminal was connected to a platinum wire and touched to the top of the KOH. The results were spectacular. Davy wrote:

"The potash began to fuse at both its points of electrization. There was a violent effervescence at the upper surface; at the lower, or negative surface, there was no liberation of elastic fluid (gas), but small globules having a high metallic lustre, and being precisely similar in visible characters to quicksilver, appeared, some of which burnt with explosion and bright flame, as soon as they were formed, and others remained, and were merely tarnished, and finally covered with a white film which formed at their surfaces."

According to Davy's brother, when Davy saw the globules of potassium metal break through the potash and burst into flame, "he could not contain his joy- he actually bounded about the room in ecstatic delight". A few days later, the experiment was repeated with sodium hydroxide, and sodium metal was discovered.

Related Questions

How were substances recognized as elements before modern instrumentation?

References and Web Links

A Short History of Chemistry, J. R. Partington, Macmillan, London (1937).

Author: Fred Senese senese@antoine.frostburg.edu



General Chemistry Online! Who discovered potassium and sodium?

Copyright © 1997-2010 by Fred Senese
Comments & questions to fsenese@frostburg.edu
Last Revised 08/17/15.URL: http://antoine.frostburg.edu/chem/senese/101/history/faq/sodium-discovery.shtml