Chemical Formula
Pa
Background
Kasimir Fajans and O.H. Göhring first produced protactinium-234 in 1913 while examining the radioactive decay of uranium. They named the element brevium, which means brief. Following this, two groups of scientists Otto Hahn and Lise Meitner from Germany and John Cranston and Frederick Soddy from Great Britain independently confirmed the existence of protactinium-231. However, Aristid V. Grosse was the first to isolate protactinium from its oxide by converting it to iodide and decomposing it using a high vacuum heated filament.
Basic Information
| Name |
Protactinium |
| Symbol |
Pa |
| Atomic number |
91 |
| Atomic weight |
231.035 amu |
| Standard state |
Solid at 298 K |
| CAS Registry ID |
7440-13-3 |
| Group name |
Actinoid |
| Period in periodic table |
7 |
| Block in periodic table |
f-block |
| Color |
Silvery metallic |
| Classification |
Metallic |
| Melting point |
1845 K (1572°C or 2862°F) |
| Boiling point |
Unknown |
| Density |
15.37 g/cm3 |
| Phase at room temperature |
Solid |
Occurrence
Protactinium is naturally available in pitchblende-uranium ores in concentrations up to 3 ppm. Very small quantities of protactinium are also present in the Earth's crust.
Protactinium (version 1) - Periodic Table of Videos
Isotopes
Protactinium has around 27 isotopes with mass numbers in the range of 212Pa to 238Pa. It has no stable isotopes.
The following are the longest-lived isotopes of protactinium:
- 231Pa with a half-life of 32,760 years
- 233Pa with a half-life of 26.967 days
- 230Pa with a half-life of 17.4 days.
Production
Protactinium can be prepared as a by-product of uranium processing. It can also be produced as an intermediate product of nuclear fission in thorium with neutrons in the high-temperature reactors.
23290Th + 10n → 23390Th → 23391Pa → 23392U
It can also be prepared by reducing anhydrous fluoride with calcium, barium or lithium.
Key Properties
The key properties of protactinium include the following:
- It is extremely radioactive
- It easily reacts with acids, water vapor and oxygen
- It is paramagnetic.
Applications
Protactinium is used mainly for research purposes only.
References
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