Is Hydrogen Fluoride (HF) Ionic or Covalent?

Is Hydrogen Fluoride (HF) ionic or covalent?

HF sits near the boundary between polar covalent and ionic. Fluorine (EN 3.98) strongly pulls shared electrons from hydrogen (EN 2.20), creating significant partial charges.

FormulaHF
NameHydrogen Fluoride
Bond TypePolar Covalent
EN ValuesH: 2.2, F: 3.98
EN Difference1.78
Electron BehaviorUnequal sharing
Melting Point-83 C (low for polar)
ConductivityWeak conductor in solution
SolubilitySoluble in water
Key ConceptHigh polarity near the ionic/covalent boundary

Overview

Hydrogen fluoride has one of the most polar covalent bonds. It sits right at the boundary between polar covalent and ionic character.

Electronegativity Analysis

Hydrogen has an EN of 2.20, fluorine has 3.98 (the highest of any element). The difference of 1.78 is near the 1.7 ionic threshold.

Electron Behavior

Electrons are shared but strongly pulled toward fluorine. This creates large partial charges, almost but not quite reaching full electron transfer.

Physical Properties

Despite having just two atoms, HF is a liquid at room temperature due to strong hydrogen bonding. It is a weak acid in water (pKa 3.17).

See electronegativity values, partial charges, and bond character on interactive 3D molecules.

Visualize Hydrogen Fluoride's Bonding in 3D

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