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Atomic Number : 91Atomic Symbol : PaAtomic Weight : 231.03588Melting Point : 2,862 F ( 1,572 C)Boiling compass point : 7,232 F ( 4,000 light speed )
Word Origin : The word protactinium come from the Greekprotos , meaning first , and actinium . In issue , it means “ parent of actinium ” becauseactiniumis a disintegration mathematical product of protactinium ’s radioactive decay .
Protactinium
find : The existence of protactinium was predicted in 1871 by Dmitri Mendeleev . Discovery of the element is assign to Otto Hahn and Lise Meitner , who discovered another isotope of protactinium,231 Pa in 1917 . The chemical element was n’t set apart until 1934 , by Aristid von Grosse .
Properties of protactinium
As a metal , protoactinium is dull and silvery - gray with a bright metal lustre , which it keep on for some sentence in atmosphere . It is superconductive below 1.4 K ( minus 457.2 F ) . It readily oppose withoxygen , pee vapor , and inorganic acids to form various compounds . Some of the compound are color . [ SeePeriodic Table of the Elements ]
When in compound form , atomic number 91 is most stable in oxidisation nation +5 , though it also exists in +4 , +3 and +2 oxidation state . In result the +5 state , it rapidly hydrolyzes by combine with hydroxide ion to organise soluble or indissoluble hydroxy - oxide solids . These solids tend to stick to to the surfaces of vessels in which they are contain .
The element is a dangerous highly radioactive alpha emitter ( 5.0 MeV ) and requires precautions similar to those used when wield plutonium .
Sources of protactinium
One of the rarified naturally occurring elements , protactinium occurs in Earth ’s insolence in average concentrations of a few parts per trillion . This rarity take in it one of the most expensive born element .
It may be found in somewhat greater numbers of a few character per million in some uraninite ore deposits , and in pitchblende at about one part231 Pa to 10 million parts of ore . Ores from Zaire have about 3 ppm .
Uses of protactinium
Due to its scarcity , high perniciousness , and high radioactivity , protactinium has no current practical utilization other than basic scientific research .
Isotopes
Protactinium has 29 radioisotopes . Almost all naturally occurring protactinium is231 Pa. It has a half - life of 32,700 years and is an alpha emitter make by the decay of235U. Other uranium decays grow isotopes of atomic number 91 . Nearly all uranium-238 ( 99.8 percent ) crumble first to the234mPa isomer and then to234 Pa.
( Source : Los Alamos National Laboratory )
