Element: Fluorine
General data
| Element name | Fluorine |
|---|---|
| Chemical symbol | F |
| Atomic number Z | 9 |
| Year discovered | 1670 |
| Standard state (25°C) | Gas |
| Category | Halogen |
| Block | p |
| Atomic mass | 18.998 |
| CPK color | #90E050 |
Physical properties
| Melting point | 53.53 K (-219.62 °C) |
|---|---|
| Boiling point | 85.03 K (-188.12 °C) |
| Density | 0.001696 g/cm³ |
Energy properties
| First ionization energy | 17.423 eV |
|---|---|
| Electron affinity | 3.339 eV |
Atomic structure
| Protons | 9 (Atomic number) |
|---|---|
| Neutrons (F-19, most abundant isotope) | 10 |
| Electrons | 9 |
| Electron configuration | [He] 2s² 2p⁵ |
| Oxidation states | -1 |
| Electronegativity (Pauling) | 3.98 |
| Atomic radius (van der Waals) | 135 pm |
Ionization energies - NIST ASD (9 states)
| State | Charge | Ioniz. energy (eV) | Type |
|---|---|---|---|
| F I | 0+ | 17.42282 ± 0.00005 | measured |
| F II | 1+ | 34.97081 ± 0.00012 | measured |
| F III | 2+ | 62.70798 ± 0.00025 | semi-empirical |
| F IV | 3+ | 87.175 ± 0.017 | semi-empirical |
| F V | 4+ | 114.249 ± 0.006 | semi-empirical |
| F VI | 5+ | 157.16311 ± 0.00025 | measured |
| F VII | 6+ | 185.1868 ± 0.0006 | measured |
| F VIII | 7+ | 953.8983 ± 0.0003 | calculated |
| F IX | 8+ | 1103.1175302 ± 0.0000019 | calculated |
Value type as given by NIST ASD: measured - from evaluated experimental data; calculated - from ab initio calculations (mostly highly ionised atoms that have not been measured; for the simplest ones, e.g. H I, the calculation is more accurate than measurement); semi-empirical - from interpolation, extrapolation or another semi-empirical method.
Photos
Isotopes (18)
| A | N | Half-life | Decay |
|---|---|---|---|
| F-14 | 5 | unbound (resonance) | p |
| F-15 | 6 | unbound (resonance) | p |
| F-16 | 7 | unbound (resonance) | p |
| F-17 | 8 | 64.37 s | EC/β⁺ |
| F-18 | 9 | 109.734 min | EC/β⁺ |
| F-19 | 10 | stable | - |
| F-20 | 11 | 11.006 s | β⁻ |
| F-21 | 12 | 4.158 s | β⁻ |
| F-22 | 13 | 4.23 s | β⁻ |
| F-23 | 14 | 2.23 s | β⁻ |
| F-24 | 15 | 384 ms | β⁻ |
| F-25 | 16 | 81 ms | β⁻ |
| F-26 | 17 | 8.6 ms | β⁻ |
| F-27 | 18 | 5.3 ms | β⁻ |
| F-28 | 19 | unbound (resonance) | n |
| F-29 | 20 | 3.3 ms | β⁻ |
| F-30 | 21 | < 250 ns | n |
| F-31 | 22 | unknown | β⁻ |
Data sources
- PubChem Periodic Table API - Retrieved on 29 June 2026 - licence: CC0
- IUPAC CIAAW - Abridged Standard Atomic Weights 2024 - Table version: 2024 - licence: Public domain
- NNDC Wallet Cards 2023 - Data as of 15 October 2024 - licence: Public domain
- NIST Atomic Spectra Database (ASD) - Retrieved on 29 June 2026 - licence: © U.S. Secretary of Commerce
- Images of Elements - Retrieved on 29 June 2026 - licence: CC BY 3.0