Francium
Francium is a chemical element with the chemical symbol Fr and an atomic number of 87. It is a metal. In chemistry it is placed in a group of metal elements named the alkali metals. Francium is very radioactive. It is in very small amounts in uranium and thorium ores. It has the lowest electronegativity and electron affinity of all the chemical elements.
Francium reacts violently with water, as do all of the elements in group 1 on the periodic table.
Francium is one of the hardest to find elements on the planet Earth. It is estimated that there are only about 15 grams or half an ounce in the Earth’s crust at a single time.
Although chemists knew the element number 87 in the periodic table should exist, it was a long time before it was discovered. In the early 1900s, nearly all boxes on the periodic table had been filled. Chemists knew that one element had been found to fit into each box. Francium was discovered in 1939 by a French chemist called Marguerite Perey. She named it after her home country, France.
Isotopes
There are 34 known isotopes of francium ranging in atomic mass from 199 to 232. Francium-223 and francium-221 are the only isotopes that occur in nature.
Francium-223 is the most stable isotope, with a half-life of 21.8 minutes. Francium-223 is the fifth product of the actinium decay series as the daughter isotope of actinium-227. Francium-223 then decays into radium-223 by beta decay (1.149 MeV decay energy), with a minor (0.006%) alpha decay path to astatine-219 (5.4 MeV decay energy).
Francium-221 has a half-life of 4.8 minutes. It is the ninth product of the neptunium decay series as a daughter isotope of actinium-225. Francium-221 then decays into astatine-217 by alpha decay (6.457 MeV decay energy).
Written for younger readers
Francium, in simpler words
This version comes from Wikijunior, a set of books written for children aged 8 to 11. It is shorter and uses plainer language than the article above.
From Wikijunior: The Elements
NOTOC
Francium is a very unstable metal. Francium is thought to have a silvery and gray color to it. No one has tasted francium because it is very rare, toxic and radioactive. Scientists cannot study francium directly. It exists only in trace amounts and disappears too quickly. Francium-223, has a half-life of only 22 minutes. Scientists are unable to collect enough to examine. The largest sample ever created contained only about 300,000 atoms—an amount too small to see with the naked eye.
Francium was discovered in 1939 by Marguerite Perey of the Curie Institute, in Paris, France.
At the time, she was researching the radioactive decay of actinium-227. Her research indicated there was another element hidden in her sample. She deduced the missing element was number 87. Her results were challenged by other scientists. She was not credited with the discovery of francium until 1946.
Francium is the last naturally occurring element that has been discovered. Later discoveries were all synthetic elements created in laboratories. To make synthetic elements, scientists use particle accelerators and nuclear reactors. These machines smash atoms together to create new elements that do not exist in nature.
Marguerite Perey named francium after France, her home country.
It was once called eka-caesium. “Eka” is a Sanskrit word meaning “one” (one place below caesium on the periodic table). Eka caesium was a “placeholder” word indicating where a new element would be placed on the periodic table when it was discovered.
After Perey’s discovery, the name “catium” was suggested, but people thought English speakers would associate the name with cats.
There is very little naturally occurring francium on earth. Small amounts of francium are found with uranium and thorium ores. Scientists estimate there are only 20–30 grams of francium in the entire Earth’s crust—less than a handful spread across the whole planet. Francium is found in uranium minerals such as pitchblende (uraninite). Scientists can make synthetic francium in the laboratory. It decays quickly, making it difficult to study.
Francium has a short half-life of about 22 minutes. It is so unstable, it would decompose to other elements quickly. So, there are no known uses for francium based on the research.
Francium is not practical for making things that people use. It may be used in medicine someday. It may be used in the future by geologists to tell the age of rocks. These ideas are not practical today.
Francium is very dangerous because it is radioactive. Scientists hypothesize it would react instantly with air (oxidize) and react violently with water (explode).
Intense heat and hydrogen gas would be released. Radioactive contamination would make it very dangerous.
Where this page comes from
The article above is adapted from “Francium” on Simple English Wikipedia, by its contributors. We removed reference markers, navigation boxes and tables, expanded measurement templates into readable numbers, and kept the prose otherwise intact. The simpler version is adapted from Wikijunior on Wikibooks.
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