Other Free Encyclopedias » 21st Century Webster's Family Encyclopedia » 21st Century Webster's Family Encyclopedia - Pope to Proverbs, Book of



Protactinium, chemical element, symbol Pa; for physical constants see Periodic Table. Discovered in 1917 by 2 teams of scientists working independently; Otto Hahn and Lise Meitner of Germany and Frederick Soddy and John Cranston of Great Britain. It is found in the mineral pitchblende in minute quantities. Protactinium is a lustrous, radioactive metal, and a member of the actinide series. The element was initially prepared by decomposing its iodide in a vacuum with an electrically heated filament. The longest lived is an alpha emitter with a half-life of 32,500 years. It is a dangerous and toxic material.

Protagoras [next] [back] Prostitution

User Comments

Your email address will be altered so spam harvesting bots can't read it easily.
Hide my email completely instead?

Cancel or