Krypton difluoride, or KrF2, has the Lewis structure of a krypton atom with 3 lone pairs, single bonded to two fluorine atoms, each also containing 3 lone pairs. Krypton has 8 valence electrons, whereas fluorine contains 7 valence electrons.
A lone pair is a valence electron pair not shared with other atoms. The single bonds between the krypton atom and the fluorine atoms leave the krypton atom with 6 valence electrons, as well as for each fluorine atom. Krypton difluoride was the first compound of krypton discovered and is a colorless, volatile solid as well as a linear molecule. This compound is highly reactive with strong Lewis acids - substances that accept electrons from other chemical species - to form salts of the KrF+and Kr2F3+ cations.