protactinium


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protactinium

 (Pa) [pro″tak-tin´e-um]
a chemical element, atomic number 91, atomic weight 231. (See Appendix 6.)

pro·tac·tin·i·um (Pa),

(prō'tak-tin'ē-ŭm),
A radioactive element, atomic no. 91, atomic wt. 231.03588, formed in the decay of uranium and thorium; its most long-lived isotope, 231Pa, has a half-life of 32,500 years.
Synonym(s): proactinium, protoactinium
[G. prōtos, first]

pro·tac·tin·i·um

(Pa) (prō'tak-tin'ē-ŭm)
A radioactive element, atomic no. 91, atomic wt. 231.03588, formed in the decay of uranium and thorium; its longest-lived isotope, 231Pa, has a half-life of 32,500 years.
[G. prōtos, first]
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References in periodicals archive ?
Under Marchal's direction, she is using mathematical models to understand how two heavy elements, protactinium and thorium, can reveal how the Atlantic Ocean circulated in the past.
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The six following elements (No.'s 84 to 89) are radioactive and exist in Nature in insignificant quantities, and are followed by the significant radioactive elements thorium, protactinium and uranium (Z = 90, 91, and 92 respectively).
Upper limit of the periodic table and synthesis of superheavy elements
Hahn and Meitner, who had discovered protactinium (see 1917), were investigating the matter.
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