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Astronomy Chemical element

Fluorine

Fluorine (F) is a halogen with atomic number 9 and atomic mass 18.9984 u. This data sheet describes its fundamental properties, position in the periodic table, and physical characteristics.

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Astronomy · Chemical element

Fluorine

EL9

Identity

  • Name: Fluorine
  • Symbol: F
  • Atomic number: 9
  • Atomic mass: 18.9984 u

Position in the periodic table

  • Group: 17 (VIIA)
  • Period: 2
  • Block: p-block
  • Category: Halogen

Physical and chemical properties

  • Standard state (25 °C, 1 atm): Gas
  • Melting point: −219.67 °C
  • Boiling point: −188.11 °C
  • Density (at boiling point): 1.696 g/L
  • Electron configuration: [He] 2s² 2p⁵

Scientific description

Fluorine is the chemical element with symbol F and atomic number 9. It is the lightest halogen and the most electronegative element (Pauling electronegativity 3.98). At standard conditions it exists as a pale yellow diatomic gas F₂ and is extremely reactive.