Francium: Occurrence, Properties, Uses and Isotopes of Francium


Francium is a highly radioactive element classed as an alkali metal located in group number 1 and period number 7 of the periodic table. Its atomic number is 87 whereas its atomic mass is 223.

Francium has 87 electrons in a single atom. It contains 87 protons and 136 neutrons in its nucleus. The element Francium is represented by the symbol “Fr”.

Naming and History

Francium was named after the country name “France”. It is because it was discovered in the Curie Institute of France.

  • Marguerite Perey

In 1939, Marguerite Perey discovered francium while she was studying and researching the radioactive decay of another radioactive element – actinium- 227.  The research was actually started in 1935 when she read the research papers of scientists claiming that actinium has beta particles with energy more than normal.

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She started her own experiments and found that actinium activity was caused by alpha particles, not by beta particles. She found that actinium can decay by eliminating the helium nucleus. That nucleus was previously an undiscovered element that she named francium after her country.

The discovery of the element francium completed the discovery of all naturally occurring elements by humans.

Occurrence of Francium

After astatine, francium is the second rarest element present on Earth’s crust. It is an extremely rare element. It occurs naturally in uranium minerals but in extremely trace amounts. It is prepared by bombarding neutrons on radium in nuclear reactors.

The other way of obtaining francium is by bombarding protons on thorium. It occurs as the product of the alpha decay of actinium.

Properties of Francium

Francium is a highly radioactive, unstable, heavy, and least electronegative element in the periodic table. It is not present in vast quantities so most of the chemical and physical properties of francium are unknown. Because of its least electronegativity, it should be highly reactive.

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But there are no known reactions with water or other elements. The melting point of francium is between 21 ᵒC to 27 ᵒC. The boiling point of francium is 650 ᵒC. Its density is not known. At room temperature, it exists as solid.

Biological Importance of Francium

There is no known and significant role of francium in living organisms and biological systems. But it is highly toxic due to its highly radioactive nature.


Uses of Francium
  • Due to its rarity, instability, and unknown nature, it has no commercial usage. Also, its half-life is only 22 minutes which makes it difficult to use.
  • The element is prepared in nuclear reactors and used for research and study purposes.
  • It has been used in spectroscopy to some extent.
  • It is possible that it might found its usage in the diagnosis of cancer.
Isotopes of Francium

There are 33 known isotopes of francium from mass numbers ranging from 200 to 232. All of them are extremely unstable with half-lives of just a few minutes. The most stable of them all is Fr- 223 with the longest half-life of 21.8 minutes only.

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