009Reactive nonmetal · Group 17 · Period 2
Fluorine
Fluorine (F) is element 9, a reactive nonmetal in the p-block — group 17, period 2. It is a gas at room temperature with 2 electron shells (2, 7) and an atomic mass of 18.9984031636 u.
- Atomic mass
- 19.00 u
- Phase · STP
- gas
- Melting
- 53 K · -220 °C
- Boiling
- 85 K · -188 °C
- Electronegativity
- 3.98
- Density
- 1.696 g/cm³
Photograph — Fulvio314, CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0>, via Wikimedia Commons
Identity
- Atomic number
- 9
- Standard atomic weight
- 19.00 u
- Category
- Reactive nonmetal
- Group
- 17 · Halogens
- Period
- 2
- Block
- p-block
- Oxidation states
- -1
Physical properties
- Melting point
- 53 K · -220 °C
- Boiling point
- 85 K · -188 °C
- Density
- 1.696 g/cm³
- Molar heat capacity
- —
- Atomic radius
- 135 pm
- Electron affinity
- 328.1649 kJ/mol
Atomic structure
9protons
10neutrons
9electrons
7valence e⁻
- Noble-gas notation
- [He] 2s2 2p5
- Full configuration
- 1s2 2s2 2p5
- Electrons per shell
- 2, 7
Periodic trends
Where Fluorine ranks across all 118 elements.
Ionization energies
Energy to remove each successive electron (kJ/mol).
1.7k1
3.4k2
6.1k3
8.4k4
11.0k5
15.2k6
17.9k7
92.0k8
106.4k9
Successive ionization energies (kJ/mol, log scale).
Discovery
- Discovered
- 1670
- Discovered by
- André-Marie Ampère
- Named by
- Humphry Davy
- Appearance
- —