Francium is a heavy alkali metal. In the periodic table, it is positioned in the last row (or seventh period) of group IA. Chemically, it is represented by the symbol Fr. Francium is the last element to be discovered among all the naturally occurring elements found on the surface of the Earth. The credit for discovering this metallic element goes to French physicist Marguerite Perey. In 1939, when she was working in Curie Institute in Paris, France, she analyzed the radioactive decay of the element Actinium. At that time, she observed that almost 99% of Actinium disintegrated into Thorium, and the remaining 1% changed to an element with atomic number 87. She named this newly discovered element Francium after her motherland, France, where it was discovered.
Some of the important physical characteristics that distinguish Francium from other chemical elements are as follows:
- Standard state (phase): Solid
- Color: Metallic
- Melting point: 300K or 27 °C or 80 °F
- Boiling point: 950K or 677 °C or 1250 °F
- Density: 1.87g per cubic centimeter
The distinguishing features of the atoms of this element determine its chemical properties. A few of them are listed below:
- Atomic number: 87
- Atomic mass: 223.0197
- Electrons per shell: 2,8,18,32,18,8,1
- Oxidation state: 1 (strong basic oxide)
Francium is extremely rare in nature. In fact, it is the second rarest element after Astatine. Experienced researchers believe that there are hardly 30 grams of this element found on the surface of the Earth. The natural form of Francium is available in trace amounts in minerals of Uranium, and Thorium. It can also be obtained by artificially by bombarding Thorium atoms with fast-moving protons. It can also be produced by bombardment of Radium atoms with neutrons.
The electronegativity of this element is the lowest among all the chemical elements. For this reason, it is highly reactive in nature. As very small quantities of this element are found on Earth, very little practical information is available about its chemistry. Theoretically, it has been proved that it is the most chemically active alkali metal. It would react violently with water. This reaction is a lot more vigorous than the reaction between sodium and water.
Francium is a radioactive metal. In other words, it has a very unstable nucleus. The half-life period of this radioactive element is barely 22 minutes. On radioactive disintegration, it decays into Astatine, Radium, and Radon.
In all, there are 34 isotopes of this element. The atomic mass of these isotopes lies in between 199 and 232. Out of them, only two are naturally occurring isotopes of the element. They are: Francium-223 and francium-221. Francium 223 is more commonly found as it is comparatively more stable. All the remaining 32 isotopes are produced artificially.
There are no commercial uses of Francium. This is mainly because of the fact that it is not easily available and its half-life period is very short. Its uses are mostly confined to research laboratories where it is studied to gather information about its atomic structure, and possible biological uses.
So far, there are no known adverse effects of this element on human health. However, as it is extremely radioactive, it is bound to be a major health hazard for humans.