Krypton difluoride

Krypton difluoride (KrF₂) is a colorless, volatile noble-gas compound and one of the strongest known oxidizing and fluorinating agents.

Molecular orbital theory: A model of chemical bonding that describes electrons as occupying orbitals spread over molecules. It explains KrF₂’s three-center, four-electron bonding across the linear F–Kr–F unit.
Noble-gas chemistry: The chemistry of elements in Group 18, including their compounds and reactions. KrF₂ is a central example of a compound formed by a traditionally inert noble gas.
Neil Bartlett: A British chemist who demonstrated in 1962 that xenon could form a stable chemical compound. His xenon chemistry inspired the search for compounds of other noble gases, including krypton.
Krypton: A colorless noble gas with atomic number 36 and a filled outer electron shell. Its closed-shell atom is the central atom in krypton difluoride.
Three-center four-electron bond: A covalent bonding arrangement in which four electrons are shared across three atoms. This bonding model accounts for the stability of linear KrF₂ despite krypton’s closed shell.
Xenon difluoride: A noble-gas compound with formula XeF₂, used as a fluorinating and silicon etching reagent. It is a more stable, widely used analogue with similar linear structure and fluorinating chemistry.
Noble-gas compounds: Chemical compounds containing one or more elements from Group 18. KrF₂ belongs to a class whose discovery overturned the idea that noble gases were wholly inert.
Fluorine: A highly reactive chemical element with atomic number 9 and the greatest electronegativity. Fluorine’s strong attraction for electrons drives KrF₂ formation and reactivity.
VSEPR theory: A model that predicts molecular shape by treating electron domains around a central atom as mutually repelling. It predicts the linear molecular shape from krypton’s five electron domains.
Fluorination: A chemical process that introduces fluorine atoms into a molecule or material. KrF₂ performs selective fluorination under conditions distinct from elemental fluorine.

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