---
title: "Francium (Fr): Atomic Mass, Electron Configuration & Properties"
url: https://www.moldraw.com/elements/francium.html
description: "Francium (Fr), element 87: atomic mass [223], electron configuration [Rn] 7s¹, group 1, period 7, s-block alkali metal. Melting and boiling point, density, electronegativity and shells."
lang: en
publisher: Scidart Academy
generated: 2026-11-03
---
87Fr[223]

# Francium (Fr) – element 87

Francium is a chemical element with the symbol **Fr** and atomic number **87**. It is a alkali metal in group 1 (alkali metals), period 7 of the periodic table (s-block), and is a solid at room temperature.

Francium (Fr) has atomic number 87, atomic mass [223] and electron configuration [Rn] 7s1.

[Download periodic table PDF](https://www.moldraw.com/printables/periodic-table.pdf)[Open interactive periodic table](https://www.moldraw.com/tools/free-chem-tools/interactive-periodic-table.html)

## Francium facts

| Symbol | Fr |
| --- | --- |
| Atomic number | 87 |
| Atomic mass | [223] |
| Category | alkali metal |
| Group | group 1 (alkali metals) |
| Period | 7 |
| Block | s-block |
| Phase at 20 °C | Solid |
| Electron configuration | 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s1 |
| Noble-gas notation | [Rn] 7s1 |
| Electrons per shell | 2, 8, 18, 32, 18, 8, 1 |
| Valence electrons | 1 |

## Bohr model and shells

Francium has 87 electrons in 7 shells: 2, 8, 18, 32, 18, 8, 1. Full configuration and noble-gas notation are in the table; work out any element or ion with the [electron configuration calculator](https://www.moldraw.com/tools/free-chem-tools/electron-configuration-calculator.html).

## Physical and atomic properties

| Melting point | 300 K (26.9 °C) |
| --- | --- |
| Boiling point | 950 K (676.9 °C) |
| Density | 1.87 g/cm³ |
| Electronegativity (Pauling) | 0.79 |
| Electron affinity | 46.89 kJ/mol |
| Ionization energies | 380 kJ/mol (1st) |
| Discovered by | Marguerite Perey |

Use the atomic mass in the [molar mass calculator](https://www.moldraw.com/tools/free-chem-tools/molar-mass-calculator.html) for any formula containing Fr.

## Position in the periodic table

Tap any element to open its page.

## Frequently asked questions

### What is the atomic mass of francium?

The atomic mass of francium is [223] (mass number of its longest-lived isotope, since it has no stable isotope).

### What is the electron configuration of francium?

Francium has 87 electrons: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s¹, or [Rn] 7s¹ in noble-gas notation. Electrons per shell: 2, 8, 18, 32, 18, 8, 1.

### How many valence electrons does francium have?

Francium has 1 valence electron (group 1).

### Is francium a metal?

Yes. Francium is a alkali metal.

### Where is francium on the periodic table?

Francium is in group 1 (alkali metals), period 7, in the s-block.

Data: [Periodic-Table-JSON](https://github.com/Bowserinator/Periodic-Table-JSON) (CC BY-SA 3.0); standard atomic weights from IUPAC (abridged). Values in brackets are the mass number of the longest-lived isotope.