Protactinium Facts

A dense, silver-gray chemical metallic element, protactinium ranks high among some of the costliest elements that occur naturally. This chemical element is highly reactive when exposed to oxygen, inorganic acids and water vapor and its concentrated presence in the Earth's crust is extremely limited. It often occurs as a trillionth fraction of the Earth's crust at most places but its concentration may be higher in areas which are rich in deposits of uraninite ores. At such places, the fraction of concentration may go as high as a few parts of a million. Let's take a look at some interesting facts about protactinium to get to know this rare, lesser known naturally occurring metal of chemistry more closely.

Protactinium Properties

Before proceeding to lift the veil off the facts about protactinium, let's take a look at its properties. Check out the following table of protactinium properties.

Properties of Protactinium
Symbol	Pa
Atomic Number	91
Element Category	Actinide
Group	N/A
Period	7
Block	f
Standard Atomic Weight	231.03588g.mol-1
Electrons per shell	2, 8, 18, 32, 20, 9, 2
Phase	Solid
Density (near room temperature)	15.37 g.cm-3
Melting Point	1568°C
Electronegativity	1.5 (Pauling Scale)
Atomic Radius	163 pm
Covalent Radius	200 pm
Atomic Mass	231.03588 unified amu
Lattice Structure	Tetragonal
Lattice Constant	3.920
Magnetic Ordering	Paramagnetic
Number of Neutrons	140

Facts About Protactinium

Check out the following protactinium facts to get a closer insight into this very rare and extremely costly metallic element. These facts about protactinium will surely reveal a lot about this least known element on the periodic table.

• Protactinium was discovered in the year 1913 by Kasimir Fajans and Oswald Helmuth Göhring. Before its identification, the possibility of existence of a chemical element between thorium and uranium was predicted by Dmitri Medeleev in the year 1871.
• A different isotope of protactinium was discovered by a team led by German scientists Otto Hahn and Lise Meitner and another team led by British scientists Frederick Soddy and John Cranston independently.
• Protactinium occurs in two isotopes - ²³¹Pa and ²³⁴Pa. There are two different energy states of isotope ²³⁴Pa.
• The alpha emitting protactinium is formed from uranium-235 decay whereas the beta radiating protactinium isotope ²³⁴Pa is formed from uranium-238 decay. As much as 99.8% of uranium decays to result into ²³⁴Pa first.
• Most of the protactinium is sourced from thorium that is present in nuclear reactors.
• Due to its rare occurrence, high radioactivity, toxicity and extremely expensive extraction and procurement, there are no significant uses of protactinium. Protactinium uses are mostly confined to basic scientific research.
• Since protactinium is formed from the decay of uranium which is formed in nuclear reactors, it is believed that protactinium may be a possible supporter of nuclear chain reaction which may, theoretically, be of use in making nuclear weapons. Walter Seifritz had made a similar estimate and had come up with an associated critical mass of 750±180 kg. However, this estimate has been unanimously ruled out by later scientists and physicists.
• Possibilities of using protactinium as a tracer in the fields of geology and paleoceanography have surfaced recently.
• Extremely small traces of protactinium are present in most natural objects including food and water. As a result, it is often ingested and even inhaled from the air we breathe. Since the traces of its presence are insignificant to the extent of nearly being non-existent, the toxicity and radioactivity of protactinium do not adversely affect our systems. Out of this trace amount of protactinium that we ingest, only about 0.05% is absorbed by the body while the remaining is expelled via excretion.

That was a crisp listing of some interesting protactinium facts. The chemical compounds formed by protactinium mostly contain this element in the oxidation state +5, though its occurrence in +4, +3 and +2 states are also possible.