---
title: "Fluorine (F): Atomic Mass, Electron Configuration & Properties"
url: https://www.moldraw.com/elements/fluorine.html
description: "Fluorine (F), element 9: atomic mass 18.998, electron configuration [He] 2s² 2p⁵, group 17, period 2, p-block reactive nonmetal. Melting and boiling point, density, electronegativity and shells."
lang: en
publisher: Scidart Academy
generated: 2026-11-03
---
9F18.998

# Fluorine (F) – element 9

Fluorine is a chemical element with the symbol **F** and atomic number **9**. It is a reactive nonmetal in group 17 (halogens), period 2 of the periodic table (p-block), and is a gas at room temperature.

Fluorine (F) has atomic number 9, atomic mass 18.998 u and electron configuration [He] 2s2 2p5.

[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)

## Fluorine facts

| Symbol | F |
| --- | --- |
| Atomic number | 9 |
| Atomic mass | 18.998 u (g/mol) |
| Category | reactive nonmetal |
| Group | group 17 (halogens) |
| Period | 2 |
| Block | p-block |
| Phase at 20 °C | Gas |
| Electron configuration | 1s2 2s2 2p5 |
| Noble-gas notation | [He] 2s2 2p5 |
| Electrons per shell | 2, 7 |
| Valence electrons | 7 |

## Bohr model and shells

Fluorine has 9 electrons in 2 shells: 2, 7. 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 | 53.48 K (-219.7 °C) |
| --- | --- |
| Boiling point | 85.03 K (-188.1 °C) |
| Density | 1.696 g/L |
| Electronegativity (Pauling) | 3.98 |
| Electron affinity | 328.165 kJ/mol |
| Ionization energies | 1681, 3374.2, 6050.4 kJ/mol (1st, 2nd, 3rd) |
| Discovered by | André-Marie Ampère |

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 F.

## Position in the periodic table

Tap any element to open its page.

## Frequently asked questions

### What is the atomic mass of fluorine?

The atomic mass of fluorine is 18.998 u, so one mole of fluorine atoms weighs 18.998 g.

### What is the electron configuration of fluorine?

Fluorine has 9 electrons: 1s² 2s² 2p⁵, or [He] 2s² 2p⁵ in noble-gas notation. Electrons per shell: 2, 7.

### How many valence electrons does fluorine have?

Fluorine has 7 valence electrons (group 17).

### Is fluorine a metal?

No. Fluorine is a nonmetal (reactive nonmetal).

### Where is fluorine on the periodic table?

Fluorine is in group 17 (halogens), period 2, in the p-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.