Francium (Fr) – Periodic Table (Element Information & More)

This is a SUPER easy guide on Francium element.

In fact, the table mentioned below is the perfect information box (Which gives you every single detail about the Francium element in Periodic table.)

So if you want to know anything about Francium element, then this guide is for you.

Let’s finish this very quickly.

Francium Element (Fr) Information

State (at STP)	Solid
Position in Periodic table	Group: 1, Period: 7, Block: s
Category	Alkali metals
Atomic number or  Protons	87
Neutrons	136
Electrons	87
Symbol	Fr
Atomic mass (most stable isotope)	223 u
Electrons arrangement or  Bohr model	2, 8, 18, 32, 18, 8, 1
Electronic configuration	[Rn] 7s1
Atomic radius	348 picometers (van der Waals radius)
Valence electrons	1
1st Ionization energy	3.9 eV
Electronegativity	0.7 (Pauling scale)
Crystal structure (predicted)	BCC (body centered cubic)
Melting point	300 K or 27 °C or 81 °F
Boiling point	950 K or 677 °C or 1251 °F
Density (estimated)	2.48 g/cm3
Main isotope	123Fr
Who discovered Francium and when?	Marguerite Perey (in 1939)
CAS number	7440-73-5

Francium in Periodic table

Francium element is in group 1 and period 7 of the Periodic table. Francium is the s-block element and it belongs to alkali metals group.

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Why is Francium in Group 1?

Do you know, how many electrons can be accommodated in the first shell, second shell, third shell, fourth shell, etc…?

Here is the table showing the capacity of orbits to hold electrons. 

Number of electrons in shells.

Orbit / Shell (n)	Maximum no. of electrons this orbit can hold (2 × n2)
K shell, n = 1	2 × 1² = 2
L shell, n = 2	2 × 2² = 8
M shell, n = 3	2 × 3² = 18
N shell, n = 4	2 × 4² = 32
. . .	. . .

Thus, 

• 1st shell can hold 2 electrons.
• 2nd shell can hold 8 electrons.
• 3rd shell can hold 18 electrons.
• 4th shell can hold 32 electrons, and so on…

Now the atomic number of Francium (Fr) is 87.

Hence the francium element has electrons arrangement 2, 8, 18, 32, 18, 8, 1.

This electron arrangement indicates that the outermost orbit of francium element (Fr) has 1 electron.

Hence, it lies in group 1.

Why is Francium in Period 7?

Let me ask you a question.

How many shells does francium have?

It’s 7. Right? 

You have already seen the bohr model of francium atom in the above table.

From the Bohr model, it can be found that the number of orbits or shells in francium is 7. Hence, as francium has 7 orbits, it lies in period 7 of the Periodic table. 

Why is Francium in s-block?

Before knowing this reason, first of all I want to ask you a simple question.

How can you determine the blocks-wise position of elements?

The simple answer: The elements will lie in the s, p, d or f block will completely depend upon the subshell in which the last electron will enter.

For example; the electron configuration of francium is [Rn] 7s¹.

So the last electron of francium enters the s-subshell or s-orbital. 

Hence, francium is the s-block element.

5 Interesting facts about Francium

Interesting facts about francium element are mentioned below.

1. The name “Francium” came from the name of the country “France ”, because this element was discovered from France.
2. Francium was discovered by Marguerite Perey in 1939, in Paris.
3. Francium is the most unstable alkali metal on the periodic table.
4. The francium element is naturally available from the alpha decay of actinium.
5. Francium is considered to be the 2^nd rarest element found from the earth’s crust after astatine.

Properties of Francium

The physical and chemical properties of francium element are mentioned below.

Physical properties of Francium

Physical properties of francium are mentioned below.

• Francium is solid at STP. Its melting point is 27 °C, so it melts in a warm room.
• The crystal structure of francium is BCC (i.e body centered cubic), which is predicted from the extrapolation methods.
• Francium is a highly radioactive element in the alkali metals group of periodic table.
• The most stable isotope of francium has a half-life of only 22 minutes.
• The atomic mass of most stable isotope of  francium is 223 u and its estimated density is 2.48 g/cm³.

Chemical properties of Francium

Chemical properties of francium are mentioned below.

• Out of all the elements of periodic table, the francium element has the least electronegativity. Electronegativity of francium is 0.7 on the Pauling scale.
• Francium reacts violently with water and liberates hydrogen gas. Unfortunately, more amounts of francium are not available to see this reaction practically.
• The francium element has only 1 valence electron (i.e electron in the outermost orbit) and so its most common oxidation state is +1.

Uses of Francium

Francium is generally used for research work in chemistry. Francium has no commercial uses because of its scarcity and radioactive nature. 

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External resources:

1. Francium – Wikipedia. (2023, February 28). Francium – Wikipedia. https://en.wikipedia.org/wiki/Francium
2. Francium – Element information, properties and uses | Periodic Table. (n.d.). Francium – Element Information, Properties and Uses | Periodic Table. https://www.rsc.org/periodic-table/element/87/francium
3. P. (n.d.). Francium | Fr (Element) – PubChem. Francium | Fr (Element) – PubChem. https://pubchem.ncbi.nlm.nih.gov/element/Francium
4. It’s Elemental – The Element Francium. (n.d.). It’s Elemental – the Element Francium. https://education.jlab.org/itselemental/ele087.html
5. Scerri, E. (2009, November). Finding francium. Nature Chemistry, 1(8), 670–670. https://doi.org/10.1038/nchem.430
6. Francium | CCDC. (n.d.). Francium | CCDC. https://www.ccdc.cam.ac.uk/elements/francium/