Overview

Francium is a chemical element with symbol Fr and atomic number 87. It used to be known as eka-caesium and actinium K. It is the second-least electronegative element, behind only caesium.

Electron configuration

The electron configuration of Francium is [Rn] 7s1, with electron shells of 2, 8, 18, 32, 18, 8, 1.

Physical and chemical properties

Francium is classified as a alkali metal. It has an atomic mass of 223 and exists as a solid at standard conditions.

Real-world uses of Francium

Francium is a highly radioactive metal that decays into astatine, radium, and radon.

Interesting facts about Francium

Explore Francium interactively

Want to compare Francium with other elements or see it highlighted on the full table? Open the interactive periodic table and click on Fr to explore properties, trends, and neighboring elements. You can also test your knowledge with our periodic table quiz game.

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What is Francium used for?

Francium is a highly radioactive metal that decays into astatine, radium, and radon.

What is the atomic number of Francium?

The atomic number of Francium is 87, meaning it has 87 protons in its nucleus.

What is the electron configuration of Francium?

The electron configuration of Francium is [Rn] 7s1.

Is Francium a metal, nonmetal, or metalloid?

Francium is classified as a alkali metal.