Francium (Fr) is a chemical element with an atomic number of 87 in the periodic table of elements. It’s found in the amount of only 24.5 grams (0.86 ounces) at any time in Earth’s crust. Being a member of the alkali family group of the periodic table, this intensely radioactive substance is the heaviest chemical element of Group 1 (Ia). Francium has one valence electron in the s-orbital of the seventh energy level.
Chemical and Physical Properties of Francium
|Symbol of Francium||Fr|
|Uses||Since its isotopes have such short half-lives there are no commercially significant compounds of francium.|
|Description||Silver-white metal. Intensely radioactive.|
|Crystal Structure||Cubic: Body centered|
|Name Origin||Named for France, the nation of its discovery.|
|Discovered By||Marguerite Derey|
|Melting Point||21°C, 70°F, 294 K|
|Boiling Point||650°C, 1202°F, 923 K|
|Physical State||Solid at room temperature of 20°C|
|Half-life||From 16(7) ms to 22 minutes|
|Van der Waals Radius||Unknown|
|Most Characteristic Isotope||223Fr|
|Electronic Shell||[Rn] 7s1|
|The Energy of the First Ionization||375 kJ.mol-1|
|Discovery Date||In 1939 by Marguerite Perey at the Curie Institute in Paris|
With the periodic table symbol Fr, atomic number 87, the atomic mass of 223 g.mol-1, and electron configuration [Rn] 7s1, francium’s chemical properties by large resemble the properties of the other alkali metals (lithium, sodium, potassium, rubidium, and cesium). However, the ionization energy of francium is slightly higher than the one of caesium. In each energy level of its electron configuration, this alkali element carries one, two, eight, eighteen, thirty-two, and eighteen electrons, i.e. 1s2 2s2p6 3s2p6d10 4s2p6d10f14 5s2p6d10 6s2p6 7s1.
Francium is an extremely rare alkali metal that reaches its boiling point at 650°C (1202°F, 923 K), while the melting point is achieved at 21°C (70°F, 294 K). This member of the alkali family of elements in the periodic table has a +1 oxidation state and an electronegativity of 0.7 according to Pauling, whereas the atomic radius according to van der Waals is unknown.
How Was Francium Discovered?
Marguerite Catherine Perey (1909 – 1975) was a French physicist and a student of Marie Curie, employed at the Radium Institute of Paris. Perey was hired as an expert in isolation of the pure form of actinium by Marie Curie’s laboratory. In 1939, by performing the carefully planned procedures of actinium purification in her experimental trials, the French physicist noticed unusual radiation emitting from an actinium decay form.
After a long and thorough observation, Perey decided to add caesium chloride to the purified sample of the radioactive substance. This caused actinium (89Ac) to lose two protons by emitting alpha particles. In this way, a new atom that has 87 protons was produced – francium (Fr).
The element’s discovery was actually predicted by the great Russian chemist Dmitri Ivanovich Mendeleev (1834 – 1907). Namely, when Mendeleev postulated the periodic classification of the chemical elements, he had a practice of leaving empty spots in the table for the elements that he predicted should exist. His claims were made upon the basis of the unexplained radioactivity in minerals, i.e the new lines in their X-ray spectra. One of those empty spots was right beneath cesium, which in 1939 was taken by francium (Fr).
How Did Francium Get Its Name?
Element 89 (francium) was named in honor of the country of its discovery, France. This is also the native country of the discoverer of francium, Marguerite Perey, as well as the second home country of Marie Curie – the Nobel Prize-winning French scientist and Perey’s mentor at the Radium Institute of Paris.
Where Can You Find Francium?
The pure elemental form of francium occurs in nature as a result of an alpha disintegration of actinium (Ac). In most cases, it is found in uranium minerals. The bombardment of thorium with protons also produces atoms of francium.
Francium in Everyday Life
Due to the small quantities available of this intensely radioactive substance, francium is mainly used in scientific research, for chemical trials and spectroscopic experiments, as well as for early diagnostics of various types of cancer.
Most recently, francium found its application in several researches conducted at the Stony Brook University, New York, United States.
How Dangerous Is Francium?
The alpha and beta particles that are emitted by this highly radioactive element readily attack the genetic material of the cells, which triggers their mutation. Exposure to any level of radiation can lead to severe types of cancer and fatal consequences. Such was the case of the discoverer of francium, Marguerite Perey. This distinguished French nuclear physicist practically fell victim to her eagerness in bringing this new element closer to the world of science.
Environmental Effects of Francium
Being an extremely radioactive synthetically produced element, the isotopes of francium cannot be found free in nature and are characterised with an extremely short half-life. Hence, this substance has no harmful impact on the environment.
Isotopes of Francium
Since all known isotopes of francium are extremely radioactive, there are no stable isotopes of this element. They all quickly decay into astatine, radium, and radon. The 223Fr isotope is the only naturally occurring isotope of francium. With a half-life of 22 minutes, francium-223 is also the longest-lived isotope of this chemical element. It decays into radium-223 through beta decay or into astatine-219 through alpha decay.
|Z||N||Isotopic mass (Da)
[n 2][n 3]
[n 6][n 4]
|Excitation energy[n 4]|
|201Fr||87||114||201.00386(8)||67(3) ms||α (99%)||197At||(9/2−)|
|202Fr||87||115||202.00337(5)||290(30) ms||α (97%)||198At||(3+)|
|203Fr||87||116||203.000925(17)||0.55(2) s||α (95%)||199At||(9/2−)#|
|204Fr||87||117||204.000653(26)||1.7(3) s||α (96%)||200At||(3+)|
|205Fr||87||118||204.998594(8)||3.80(3) s||α (99%)||201At||(9/2−)|
|206Fr||87||119||205.99867(3)||~16 s||β+ (58%)||206Rn||(2+, 3+)|
|207Fr||87||120||206.99695(5)||14.8(1) s||α (95%)||203At||9/2−|
|208Fr||87||121||207.99714(5)||59.1(3) s||α (90%)||204At||7+|
|209Fr||87||122||208.995954(16)||50.0(3) s||α (89%)||205At||9/2−|
|210Fr||87||123||209.996408(24)||3.18(6) min||α (60%)||206At||6+|
|211Fr||87||124||210.995537(23)||3.10(2) min||α (80%)||207At||9/2−|
|212Fr||87||125||211.996202(28)||20.0(6) min||β+ (57%)||212Rn||5+|
|213Fr||87||126||212.996189(8)||34.6(3) s||α (99.45%)||209At||9/2−|
|220Fr||87||133||220.012327(4)||27.4(3) s||α (99.65%)||216At||1+|
|221Fr||87||134||221.014255(5)||4.9(2) min||α (99.9%)||217At||5/2−||Trace[n 7]|
|223Fr||Actinium K||87||136||223.0197359(26)||22.00(7) min||β− (99.99%)||223Ra||3/2(−)||Trace[n 8]|
List of Francium Compounds
The common compounds of francium include the following combinations of chemical elements:
- Francium Sulfide Fr2S
- Francium Dichromate Fr2Cr2O
- Francium Fluoride FrF
- Francium Bromide FrBr
- Francium Phosphide Fr3P
- Francium Chloride FrCl
- Francium Acetate FrC2H3O2
- Francium Carbonate Fr2CO3
- Francium Nitride Fr3N
- Francium Phosphate Fr3PO4
- Francium Oxide Fe2O4
- Francium Hydrogen Oxalate FrHC2O4
- Francium Selenide Fr2Se
- Francium Sulfate Fr2SO4
- Francium Sulfite Fr2SO3
- Francium Carbide Fr4C
- Francium Telluride Fr2Te
- Francium Permanganate FrMnO4
- Francium Oxalate Fr2C2O4
- Francium Nitrite FrNO2
- Francium Hydrogen Phosphate Fr2HPO4
- Francium Chlorite FrClO2
- Francium Hyposelenite Fr2SeO2
- Francium Thiocyanate FrSCN
- Francium Bismuthate FrBiO3
- Francium Borate Fr3BO3
- Francium Chromate Fr2CrO4
- Francium Iodate FrIO3
- Francium Metasilicate Fr2SiO3
- Francium Hydrogen Carbonate FrHCO3
- Francium Hypochlorite FrClO
5 Interesting Facts and Explanations
- Francium is the most unstable chemical of the first 101 elements in Mendeleev’s periodic system.
- The natural form of francium cannot be isolated in visible amounts due to its scarcity in Earth’s crust.
- Francium is the last natural element that has been discovered. It’s also the element with the highest equivalent weight of any other chemical.
- After astatine (As), francium is the second rarest chemical element that has been traced in Earth’s crust.
- This radioactive element is also considered to be the least electronegative of all the elements in the periodic table.