918.998FFluorine
Fluorine (F) — element 9halogen · group 17, period 2
Fluorine is a chemical element with the symbol F and atomic number 9. It is a halogen in group 17, period 2 of the periodic table (the p-block), with a standard atomic mass of 18.998 u. At room temperature (25 °C) fluorine is a gas.
💡 Known for: The most reactive and most electronegative element; fluoride protects teeth and fluorine makes non-stick PTFE coatings.
# Fluorine properties
| Symbol | F |
|---|---|
| Atomic number | 9 |
| Atomic mass | 18.998 u |
| Category | halogen |
| Group | 17 |
| Period | 2 |
| Block | p-block |
| Electron configuration | [He] 2s² 2p⁵ |
| Full configuration | 1s² 2s² 2p⁵ |
| Electrons per shell | 2, 7 |
| Protons / electrons | 9 / 9 |
| State at 25 °C | gas |
| Melting point | 53.53 K (-219.6 °C, -363.3 °F) |
| Boiling point | 85.03 K (-188.1 °C, -306.6 °F) |
| Density | 1.696 g/L |
| Electronegativity (Pauling) | 3.98 |
| First ionization energy | 17.423 eV |
| Atomic radius | 42 pm |
| Discovered | 1886 |
# Electron configuration of fluorine
The electron configuration of fluorine is [He] 2s² 2p⁵, written out in full as 1s² 2s² 2p⁵. Its 9 electrons fill 2 shells as 2, 7, so the outermost shell holds 7 electrons. As a group 17 element, fluorine has 7 valence electrons.
# Related elements
OOxygenprevious elementNeNeonnext elementClChlorinegroup 17BrBrominegroup 17IIodinegroup 17AtAstatinegroup 17TsTennessinegroup 17
# Fluorine FAQ
What is the atomic number of fluorine?
The atomic number of fluorine is 9: every fluorine atom has 9 protons in its nucleus. Its symbol is F.
What is the atomic mass of fluorine?
The standard atomic mass of fluorine is 18.998 u.
What is the electron configuration of fluorine?
Fluorine's electron configuration is [He] 2s² 2p⁵ (1s² 2s² 2p⁵), with 2, 7 electrons per shell.
Is fluorine a metal?
No. Fluorine is a halogen, a nonmetal.
What is the melting point of fluorine?
Fluorine melts at 53.53 K (-219.6 °C, -363.3 °F) and boils at 85.03 K (-188.1 °C, -306.6 °F).
What is fluorine used for / known for?
The most reactive and most electronegative element; fluoride protects teeth and fluorine makes non-stick PTFE coatings.