Francium (Fr)
Francium was the last element discovered in nature rather than first made in a laboratory.
Francium properties
- Atomic mass
- 223 u
- Category
- Alkali metal
- Group
- 1
- Period
- 7
- Block
- s-block
- State at room temp.
- Solid
- Electronegativity
- 0.79
- Melting point
- 300 K (26.9 °C)
- Boiling point
- 950 K (676.8 °C)
- Density
- 1.87 g/cm³
- Atomic radius
- 348 pm
- Ionization energy
- 3.9 eV
- Electron affinity
- 0.47 eV
- Radioactive
- Yes, no stable isotopes
- Discovered
- 1939
Francium electron configuration
- Electron configuration
- [Rn] 7s1
- Full electron configuration
- 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 6s2 6p6 7s1
- Electron shells
- 2 · 8 · 18 · 32 · 18 · 8 · 1
The electron configuration of Francium (Fr) is [Rn] 7s1. Its 87 electrons are arranged in shells as 2, 8, 18, 32, 18, 8, 1.
Protons, neutrons and electrons in Francium
A neutral Francium atom has 87 protons and 87 electrons. Most Francium atoms have about 136 neutrons: the atomic mass rounded to 223, minus the atomic number 87.
Neutrons are approximate: atoms of the same element can have different numbers of neutrons (isotopes). Atomic number and mass
How many valence electrons does Francium have?
1
Francium has 1 valence electron in its outermost shell, shell 7. These are the electrons involved in chemical bonding.
Francium orbital diagram
Each box is an orbital that holds up to two electrons with opposite spins (↑↓). The inner shells are the same as the noble gas in brackets. How to write electron configurations
Molar mass of Francium
223 g/mol
One mole of Francium atoms (6.022 × 10²³ atoms) has a mass of 223 grams. Use this value to convert between grams and moles.
Francium facts
- Francium was the last element discovered in nature rather than first made in a laboratory.
- Francium is the second rarest naturally occurring element after astatine, and no one has ever collected enough of it to see.
- Francium (Fr) has atomic number 87 and is a solid at room temperature. It was discovered in 1939.
Position in the periodic table
Francium is element 87, in period 7 and group 1 of the periodic table, in the s-block.
Uses of Francium
Francium has no practical uses because it is extremely rare and its longest-lived isotope has a half-life of only about 22 minutes. Scientists make small numbers of francium atoms in accelerators and hold them in laser traps. Because francium has a simple atomic structure and a large nucleus, it is useful for precise tests of the theory of the weak nuclear force.
Who discovered Francium?
Marguerite Perey discovered francium in 1939 at the Curie Institute in Paris while purifying samples of actinium. She named it after her home country, France.
Where does the name come from?
Francium is named after France. Marguerite Perey, who discovered the element in 1939 while working at the Curie Institute in Paris, chose the name to honor her home country.
Same group
Compare Francium
FAQ
What is the electron configuration of Francium?
The electron configuration of Francium (Fr) is [Rn] 7s1. Its 87 electrons are arranged in shells as 2, 8, 18, 32, 18, 8, 1.
How many protons, neutrons and electrons does Francium have?
A neutral Francium atom has 87 protons and 87 electrons. Most Francium atoms have about 136 neutrons: the atomic mass rounded to 223, minus the atomic number 87.
How many valence electrons does Francium have?
Francium has 1 valence electron in its outermost shell, shell 7. These are the electrons involved in chemical bonding.
What is the molar mass of Francium?
The molar mass of Francium is 223 g/mol. This is the same number as its atomic mass, 223 u.
Is Francium a metal?
Yes. Francium is an alkali metal, so it is a metal.
Is Francium radioactive?
Yes. Francium has no stable isotopes, so all of its atoms are radioactive and eventually decay into other elements.
Where is Francium on the periodic table?
Francium is element 87, in period 7 and group 1 of the periodic table, in the s-block.