Chemistry Learner

It's all about Chemistry

Home / Chemical Elements / Francium


What is Francium

Francium (pronounced as FRAN-see-em) is an alkali metal denoted by the symbol, Fr. No more than 15 grams of the element is found in the earth’s crust [1, 5].

Francium Symbol

Francium Isotopes

Its most stable isotope is Francium-223 having a half-life of 22 minutes that either undergo beta decay or alpha decay to form radium-223 and astatine-219, respectively [3].

History of Francium

How Did it Get its Name

The element has taken its name from the country, France [1].

Who Discovered Francium

It was discovered by French physicist Margaret Perey in 1939 [1].

When and How was it Discovered

Dmitri Mendeleev, the Russian chemist who first created the periodic table, had suggested the existence of an element similar to caesium yet to be discovered. After which, there were several claims, denials, and counterclaims coming from scientists who wanted to declare themselves as the first discoverer of this new element. Such claims continued to happen during the 1920’s and 1930’s based on the discovery of undetected radioactivity in some minerals and new lines in their X-ray spectra. However, when they were verified, no evidence of the suspected element was found.

It was only in 1939 when Perey, at the Curie Institute, Paris, purified the element actium to free it from radioactive impurities but still found some radioactivity in it due to the presence of the still-undiscovered francium. Many challenged her findings, and it was only after World War 2 that she was finally considered as the original discoverer of francium [1].


Classification and Position of the Element on the Periodic Table [1]

Group 1
Period 7
Block s

Location of Francium on the Periodic Table

Properties and Characteristics of Francium [1, 2, 3]

General Properties

Relative Atomic Mass (Mass Number) 223
Molar Mass 186.207 g/mol

Physical Properties

Color/Appearance Silver Gray (Unconfirmed)
Flame Color Unknown
Luster Unknown
Odor Unknown
Malleability Yes
Ductility Yes
Melting Point/Freezing Point 21°C (70°F)
Boiling Point 650°C (1202°F)
Density 21 g/cm3
State of Matter at Room Temperature Solid
Hardness (Mohs) Unknown
Electrical Conductivity (Sm-1) Unknown
Thermal (Heat) conductivity (W m-1 K-1) 3.61
Latent Heat of Fusion (kJ/mol) Unknown

Magnetic Properties

Specific Gravity Unknown
Magnetic Ordering 1
Permeability Unknown
Susceptibility Unknown

Chemical Properties

Flammability Unknown
Oxidation state/Oxidation number +1

Atomic Data of Francium [1, 2, 3]

Atomic Number 87
Valence Electrons 7s
Quantum Numbers
– n 7
– ℓ 0
– m 0
– m s +1/2
Electron Configuration (Noble Gas Configuration) [Rn] 7s1
Atomic Structure
– Number of Electrons 87
– Number of Neutrons 136
– Number of Protons 87
Energy Levels
– First Energy Level 2
– Second Energy Level 8
– Third Energy Level 18
– Fourth Energy Level 32
– Fifth Energy Level 18
– Sixth Energy Level 8
– Seventh Energy Level 1
Radius of Atom
Atomic Radius 3.48 Å
– Covalent Radius 2.42 Å
Electronegativity 0.79
Ionization Energy


1st 2nd 3rd 4th 5th 6th 7th

Bohr Model of Francium

Reaction of Francium in Water

Since the metal is alkaline, it is believed to react violently with water, producing francium hydroxide and hydrogen, and a massive amount of heat. So far, no such experiment has been conducted to prove it even though many false claims have been made showing francium exploding like a bomb when dropped in the ocean [4].

Pictures for Francium

What is Francium Used for

There are no commercial uses of francium except in basic scientific studies due to its limited production and short half-life [1, 2].

Interesting Facts

  • Among all the naturally-occurring elements, francium is the least stable one [6].
  • It can be produced by bombarding thorium with protons or radium with neutrons [2].

Francium Metal

Francium Cost

As only fewer atoms of the element have been produced in the laboratory, it is not commercially available.



4 responses to “Francium”

  1. dom says:

    give the number of shells

  2. heidi V heath says:

    The reddish example in second picture….looks exactly like rock i have that exploded (not violently) it also retains heat and can feel a weird energy around it when hot outside

  3. heidi V heath says:

    If so much is unknown then what are the pictures of? I have ores (rocks) identical to the top pic. I can tell you they do explode but not by dropping in cold water or even by spraying the rock or the water has to be warm.

Leave a Reply

Your email address will not be published.