Fluorine (F)
Halogen · p-block · period 2 · group 17
Pale yellow, highly corrosive gas.
Fluorine (symbol F) is chemical element number 9, a halogen in group 17, period 2 of the periodic table. Its standard atomic weight is 18.998 and its electron configuration is [He] 2s2 2p5. At room temperature it is a gas. The most reactive and most electronegative element — it attacks almost everything.
Properties
| Atomic number | 9 |
|---|---|
| Atomic mass | 18.998 |
| Category | Halogen |
| Block | p-block |
| Group · Period | 17 · 2 |
| Electron configuration | [He] 2s2 2p5 |
| Electrons per shell | 2, 7 |
| State at 25 °C | gas |
| Melting point | 53.48 K |
| Boiling point | 85.03 K |
| Density | 1.696 g/L |
| Electronegativity (Pauling) | 3.98 |
| Radioactive | No |
| Origin | primordial |
| Discovered | 1886 · Henri Moissan |
Key facts about Fluorine
- The most reactive and most electronegative element — it attacks almost everything.
- Isolating it took chemists nearly 75 years and cost several lives.
- Trace fluoride in water and toothpaste hardens tooth enamel against decay.
- Teflon (PTFE) is a carbon chain fully wrapped in fluorine, making it non-stick and inert.
What Fluorine is used for
Toothpaste and water fluoridation, Teflon and refrigerants, uranium enrichment, high-voltage insulation (SF6).
Where it sits in the periodic table
Fluorine is in group 17, period 2, of the p-block. Its electron configuration [He] 2s2 2p5 means its outermost shell holds 7 electrons, which is what places it here and explains much of its chemistry. See Fluorine on the interactive table →
Fluorine — frequently asked questions
What is Fluorine used for?
Toothpaste and water fluoridation, Teflon and refrigerants, uranium enrichment, high-voltage insulation (SF6).
Is Fluorine radioactive?
No. Fluorine has at least one stable isotope and is not radioactive.
What is the electron configuration of Fluorine?
Fluorine has the electron configuration [He] 2s2 2p5, which is 2, 7 electrons per shell.
What group and period is Fluorine in?
Fluorine is in group 17, period 2, in the p-block. Its outer shell holds 7 electrons.
Who discovered Fluorine?
Fluorine was discovered in 1886 by Henri Moissan.