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9F18.998
Reactive Nonmetalsgas at STPP-block

Fluorine

Group: 17Period: 2Standard Atomic Weight: 18.998 u

Why is Fluorine in this position?

Understanding the scientific rationale behind Fluorine's position in the periodic table:

Group Assignment
Group 17

Placed in Group 17 (Halogens) because it possesses 7 valence electrons (2s² 2p⁵).

Period Assignment
Period 2

Placed in Period 2 because its valence electrons fill the n=2 shell.

Orbital Block
P-block

Belongs to the p-block because its differentiating electron enters a 2p orbital.

Chemical Category
Reactive Nonmetals

Classified as a reactive nonmetal; holds the highest electronegativity on the Pauling scale (3.98).

Atomic Structure & Bohr Shell Model

Shell Distribution: [2, 7]

Bohr Atomic Shell Model(2, 7)

Hover or tap any shell orbit ring to inspect electron counts and 2n² capacities.

9 Protons (p⁺)10 Neutrons (n⁰)
KShell K: Electron 1 of 2Shell K: Electron 2 of 2LShell L: Electron 1 of 7Shell L: Electron 2 of 7Shell L: Electron 3 of 7Shell L: Electron 4 of 7Shell L: Electron 5 of 7Shell L: Electron 6 of 7Shell L: Electron 7 of 7FZ = 9

Educational Note: This Niels Bohr planetary model visually illustrates principal quantum energy shells ($n=1, 2, 3\dots$) and electron counts. In modern quantum mechanics (Schrödinger model), electrons do not orbit in fixed circular planetary tracks, but exist as 3D probability clouds (orbitals: $s, p, d, f$) governed by the Heisenberg uncertainty principle.

Electron Shell Filling Breakdown

Shell K (n=1):2 / 2 electrons (100%)
Shell L (n=2):7 / 8 electrons (88%)
Aufbau Electron Configuration
1s² 2s² 2p⁵

Neutral ground state configuration. Valence electrons: 7.

Atomic & Quantum Properties

Electronegativity (Pauling)3.98 Pauling
1st Ionization Energy1681 kJ/mol
Electron Affinity-328 kJ/mol
Atomic Radius (empirical)42 pm
Common Oxidation States-1
Crystal StructureCubic

Physical & Thermal Properties

Density at STP0.00170 g/cm³
Melting Point-219.67 °C (53.48 K)
Boiling Point-188.11 °C (85.04 K)
Magnetic OrderingDiamagnetic
Discovery Year1886
Discovered ByHenri Moissan

Real-World Uses, Occurrence & Compounds

Major Industrial & Everyday Uses
  • Non-stick polytetrafluoroethylene (PTFE / Teflon) kitchen cookware
  • Fluoride toothpaste additives for dental enamel remineralization (NaF)
  • Uranium enrichment via gaseous uranium hexafluoride (UF₆)
  • Modern pharmaceutical drugs (nearly 25% of drugs contain fluorine atoms)
Occurrence in Nature

Found as fluorite (CaF₂), cryolite (Na₃AlF₆), and fluorapatite minerals.

Etymology & Name Origin

From Latin 'fluere' meaning to flow, after the mineral fluorite

Important Chemical Compounds
HF (Hydrofluoric acid)
CaF₂ (Fluorite)
UF₆ (Uranium hexafluoride)
SF₆ (Sulfur hexafluoride)
NaF (Sodium fluoride)
Interesting Chemical Facts
  • Fluorine is so fiercely reactive that it causes water, glass, wood, and concrete to burst into flames on contact.
  • Henri Moissan received the 1906 Nobel Prize in Chemistry for finally isolating elemental fluorine after many chemists were injured.
  • The Carbon-Fluorine bond (C-F) is one of the strongest bonds in chemistry, giving Teflon its extreme chemical resistance.
Safety & Handling Note

Extremely toxic, corrosive gas; hydrofluoric acid penetrates skin painlessly to bind calcium ions, causing fatal cardiac arrest.