Protactinium – Periodic Table [Element Information & More]

protactinium element periodic table

Protactinium element (Pa) is in period 7 of a periodic table. Protactinium is in the f-block and it is classified as an actinide on the periodic table.

There is a lot more information related to protactinium which is mentioned in the Information Table given below.

So let’s dive right into it!

Table of contents

Protactinium Element (Information Table)

The important data related to protactinium element is given in the table below.

Appearance of protactiniumSilvery white metallic appearance
Atomic number of protactinium91
Symbol of protactiniumPa
Atomic mass of protactinium231.04 u
Protons, Neutrons & Electrons in protactiniumProtons: 91, Neutrons: 148, Electrons: 91
State of protactinium (at STP)Solid
Period number of protactinium in periodic table7
Block of protactinium in periodic tablef-block
Category of protactiniumInner transition metals
Bohr model or Electrons per shell or Electrons arrangement in protactinium2, 8, 18, 32, 20, 9, 2
Electron configuration of protactinium[Rn] 5f2 6d1 7s2
Orbital diagram of protactiniumorbital diagram of protactinium
Electronegativity of protactinium (on pauling scale)1.5
Atomic radius of protactinium (van der Waals radius)243 picometers
Density of protactinium15.37 g/cm3
1st ionization energy of protactinium5.89 eV
Main isotope of protactinium231Pa
Melting point of protactinium1841 K or 1568 °C or 2854 °F
Boiling point of protactinium4300 K or 4027 °C or 7280 °F
Crystal structure of protactiniumTetragonal
Discovery of protactiniumBy Kasimir Fajans in 1913

Also see: Interactive Periodic Table (It has rotating bohr models as well as many other details of all the 118 elements in a single periodic table).

Protactinium element in Periodic table

The Protactinium element (Pa) has the atomic number 91 and is located in period 7. Protactinium is a metal and it is classified as an actinide group element.

Click on above elements in the periodic table to see their information.

Facts about protactinium

Here are a few interesting facts about the protactinium element.

  1. Protactinium was given its name from the Greek word “protos” (meaning first) and “actinium”.
  2. The concentration of protactinium in the earth’s crust is around 0.1 parts per trillion (which is very very less).
  3. Protactinium is naturally obtained from uranium ores and these uranium ores contain protactinium in the concentration of 3 ppm.
  4. Protactinium is a radioactive as well as toxic metal.

Properties of protactinium

Here is a list of some physical properties and chemical properties of protactinium.

Physical properties of protactinium

  • Protactinium has a silvery white appearance.
  • Protactinium has tetragonal crystal structure.
  • The melting point and boiling point of protactinium is 1841 K and 4300 K respectively.
  • There are around 29 isotopes of protactinium and all these isotopes are radioactive in nature.
  • The density of protactinium is 15.37 g/cm3 and its atomic mass is 231.04 amu.

Chemical properties of protactinium

  • Protactinium is a toxic as well as radioactive element.
  • There are different oxidation states of protactinium, but the most common oxidation state is +5.
  • Protactinium does not show any reaction with alkalis, but it reacts with moisture, oxygen as well as acids.

Uses of protactinium

Protactinium is not used commercially because of its scarcity and radioactivity. It is generally used for research work.

External resources:

  1. Protactinium – Element information, properties and uses | Periodic Table. (n.d.). Protactinium – Element Information, Properties and Uses | Periodic Table.
  2. Prohaska, T., et al. (2022, May 1). Standard atomic weights of the elements 2021 (IUPAC Technical Report). Pure and Applied Chemistry, 94(5), 573–600.
  3. Haynes, W. M. (Ed.). (2014, June 4). CRC Handbook of Chemistry and Physics.
  4. Kaye, G W.C., & Laby, T H. Tables of physical and chemical constants. 15th Edition. United States.
  5. Sansonetti, J. E., & Martin, W. C. (2005, December). Handbook of Basic Atomic Spectroscopic Data. Journal of Physical and Chemical Reference Data, 34(4), 1559–2259.
  6. Protactinium – Wikipedia. (2019, January 9). Protactinium – Wikipedia.
  7. P. (n.d.). Protactinium | Pa (Element) – PubChem. Protactinium | Pa (Element) – PubChem.
  8. It’s Elemental – The Element Protactinium. (n.d.). It’s Elemental – the Element Protactinium.
  9. Bondi, A. (1964, March). van der Waals Volumes and Radii. The Journal of Physical Chemistry, 68(3), 441–451.
  10. Holden, et al. (2018, December 1). IUPAC Periodic Table of the Elements and Isotopes (IPTEI) for the Education Community (IUPAC Technical Report). Pure and Applied Chemistry, 90(12), 1833–2092.
  11. Zhang, et al. (2011, January 11). Corrected Values for Boiling Points and Enthalpies of Vaporization of Elements in Handbooks. Journal of Chemical & Engineering Data, 56(2), 328–337.
  12. Scerri, E. (2013, July 18). Element 91—Protactinium. A Tale of Seven Elements.

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