Periodic table › Fluorine
1. Identity and classification
Colored, pungent, reactive diatomic nonmetal (gas, volatile liquid, or crystalline solid)
- Name and symbol
- Fluorine (Fluorine) · F
- Atomic number
- 9
- Relative atomic weight / mass number
- 18.998 ± 0.001
- Group · period · block
- 17 · 2 · p
- Category
- Halogen
- State near room temperature
- Gas
- Stable isotopes
- At least one stable isotope
- CAS number
- 7782-41-4
Square brackets [A] indicate a representative isotope mass number, not an average atomic weight. Neutron counts differ between isotopes.
2. Atomic structure and electron configuration
- Protons · electrons in a neutral atom
- 9 · 9
- Neutrons in reference isotope
- 10 (19F)
- Full electron configuration
1s² 2s² 2p⁵- Abbreviated configuration
[He]2s² 2p⁵- Electrons per shell
- 2, 7
- Listed oxidation states
- -1
- Electronegativity
- 3.98 (Pauling)
- First ionization energy
- 1681.064 kJ/mol · 17.423 eV
- Electron affinity
- 322.165 kJ/mol
- Covalent radius
- 57 pm
- van der Waals radius
- 135 pm
Configurations of superheavy elements may include theoretical predictions. Different definitions of atomic radius are not interchangeable.
3. Physical and thermal properties
- Density
- 0.001696 g/cm³
- Melting point
- 53.53 K · -219.62 °C · -363.316 °F
- Boiling point
- 85.03 K · -188.12 °C · -306.616 °F
- Crystal structure
- Monoclinic
- Specific heat
- 0.824 J/(g·K)
- Thermal conductivity
- 0.0277 W/(m·K)
- Enthalpy of fusion
- 0.51 kJ/mol
- Enthalpy of vaporization
- 6.51 kJ/mol
- Magnetic ordering
- Diamagnetic
- Mohs hardness
- Not established
- Speed of sound
- 316 m/s
Density and structure depend on temperature, pressure and allotrope. 25°C is a room-temperature reference, not STP. Unestablished values are not zero.
4. Chemical behavior and compounds
Fluorine is the most electronegative element on the Pauling scale.
Selected compounds: FO / F₂O₃ (Oxide) · FClₙ (Chloride) · FFₙ (Fluoride)
Reaction reference
Fluorine is a very strong oxidizing agent.
Fluorine reacts vigorously with water, producing hydrogen fluoride and oxygen-containing products.
5. Isotopes
| Isotope | Status | Natural abundance | Half-life |
|---|---|---|---|
| 19F | Stable | 100% | Stable |
| 20F | Radioactive | — | 11.07 s |
Half-life units: s seconds, m minutes, h hours, d days, Y years. A dash means no natural-abundance value is given, not zero. Listed records are selected ground states; metastable states are distinct.
6. Discovery and occurrence
- Discovery
- 1670 CE
- Scientists associated with discovery
- Henri Moissan
- Location
- France (Paris)
- Origin
- Natural
- Listed crustal abundance
- Not established
Minerals and naming reference
Fluorite (CaF₂), Cryolite (Na₃AlF₆), Fluorapatite
Named from scientific/historical roots associated with Fluorine (F), discovered or characterized by Henri Moissan.
7. Applications
Toothpaste cavity prevention (fluoride), PTFE (Teflon) non-stick coatings, UF₆ nuclear enrichment, refrigerant gases
Detailed applications by field
- everyday
- Toothpaste cavity prevention (fluoride), PTFE (Teflon) non-stick coatings, UF₆ nuclear enrichment, refrigerant gases
- industry
- Used in halogen processing, specialized alloys, and chemical manufacturing (Toothpaste cavity prevention (fluoride), PTFE (Teflon) non-stick coatings, UF₆ nuclear enrichment, refrigerant gases).
- electronics
- Applied in electronic components, semiconductors, or functional coatings where Fluorine's electronic structure ([He] 2s² 2p⁵) provides target conductivity.
- medicine
- Diagnostic imaging, biomedical instrumentation, or pharmaceutical synthesis research.
- energy
- Utilized in power generation, battery materials, catalysts, or nuclear technology involving Fluorine.
- aerospace
- High-performance materials, structural alloys, or space instrumentation utilizing Fluorine.
- agriculture
- Soil geochemistry analysis, trace micronutrient research, or analytical environmental monitoring.
- science
- Spectroscopic standard, crystallography, and quantum chemistry studies of Period 2 p-block elements.
8. Biological role and safety
Hazard depends on the isotope, chemical form, dose and exposure route.
Elemental substances, ions, compounds and radioisotopes can have different health effects. This is an educational reference; laboratory work requires the material safety data sheet and trained supervision.
Biological role reference
Classified as trace element in human and biological systems.