francium

Also known as Fr, element 87, 87Fr, catium, eka-cesium, eka-caesium

Francium is a chemical element; it has symbol Fr and atomic number 87. It is extremely radioactive; its most stable isotope, francium-223 (originally called actinium K after the natural decay chain in which it appears), has a half-life of only 22 minutes. It is the second-most electropositive element, behind only caesium, and is the second rarest naturally occurring element (after astatine). Francium's isotopes decay quickly into astatine, radium, and radon. The electronic structure of a francium atom is [Rn] 7s1; thus, the element is classed as an alkali metal.

OverviewAI-generated

Francium is a chemical element with the symbol Fr and atomic number 87. Its standard chemical formula is Fr, and it is represented by the Unicode character 鍅. The element has an electronegativity of 0.7 and typically exhibits an oxidation state of 1. Its electron configuration is [Rn] 7s¹, and the ionic radius is 1.80.

The atomic weight of francium is 223.01973. It was discovered in 1939. In chemical databases, it is identified by the PubChem CID 6328145 and the IUPAC name francium. The substance has zero hydrogen bond donors and acceptors, with a topological polar surface area of 0. It is referenced by 425 other encyclopedia articles and has 55 associated PubMed entries.

Synthesized by Vinony from 24 facts across 4 sources: Wikidata, PubChem, PubMed, Vinony graph. Generated from structured data (not the Wikipedia text) and checked against those facts — may still contain errors.

Chemical data

Formula: Fr
Molecular weight: 223.01973 g/mol
IUPAC name: francium
SMILES: [Fr]
InChIKey: KLMCZVJOEAUDNE-UHFFFAOYSA-N
Polar surface area: 0 Å²
H-bond donors: 0
H-bond acceptors: 0
Formal charge: 0

via PubChem

Research

55 papers

Francium ion source with novel methods of target heating and beam characterization.The Review of scientific instruments · 2023Ozawa N, Nagahama H, Sakemi YDOI: 10.1063/5.0118754
Biodistribution of free Francium-221 and Bismuth-213 in Tumour-bearing SCID mice after successful development of Actinium-225/Francium-221 radionuclide generator Set-up.European journal of nuclear medicine and molecular imaging · 2025Zitzmann-Kolbe S, Remde Y, Moen I et al.DOI: 10.1007/s00259-025-07427-4
Finding francium.Nature chemistry · 2009Scerri EDOI: 10.1038/nchem.430
Nuclear Magnetic Moments of Francium-207-213 from Precision Hyperfine Comparisons.Physical review letters · 2020Roberts BM, Ginges JSMDOI: 10.1103/PhysRevLett.125.063002
Collinear resonance ionization spectroscopy of neutron-deficient francium isotopes.Physical review letters · 2013Flanagan KT, Lynch KM, Billowes J et al.DOI: 10.1103/PhysRevLett.111.212501
Hydrostatic pressure-induced transformations and multifunctional properties of Francium-based halide perovskite FrCaCl(3): Insights from first-principles calculations.Heliyon · 2024Ahmed MI, Biswas A, Asif TI et al.DOI: 10.1016/j.heliyon.2024.e34059
Gamma counting protocols for the accurate quantification of (225)Ac and (213)Bi without the need for a secular equilibrium between parent and gamma-emitting daughter.EJNMMI radiopharmacy and chemistry · 2022Castillo Seoane D, De Saint-Hubert M, Ahenkorah S et al.DOI: 10.1186/s41181-022-00174-z
[Chromatographic separation of francium].Comptes rendus hebdomadaires des seances de l'Academie des sciences · 1953PEREY M, ADLOFF JP

via PubMed

~18 min read

Encyclopedic overview

15 sections

Contents

Characteristics
Compounds
Francium perchlorate
Francium halides
Other compounds
Isotopes
Applications
History
Erroneous and incomplete discoveries
Perey's analysis
Occurrence
Production
Notes
References
External links

As a consequence of its extreme instability, bulk francium has never been seen. Because of the general appearance of the other elements in its periodic table column, it is presumed that francium would appear as a highly reactive metal if enough could be collected together to be viewed as a bulk solid or liquid. Obtaining such a sample is highly improbable since the extreme heat of decay resulting from its short half-life would immediately vaporize any viewable quantity of the element.

Excerpted from Wikipedia’s “francium” article, available under the CC BY-SA 4.0 licence.