Wiktionary
n. (context chemistry English) any chloride containing two fluorine atoms in each molecule
Wikipedia
Order and disorder in difluorides
Fluorite unit cell (ionic) - cropped.png
The fluorite structure
Difluorides are chemical compounds with two fluorine atoms per molecule (or per formula unit).
Metal difluorides are all ionic. Despite being highly ionic, the alkali earth metal difluorides generally have extremely high lattice stability and are thus insoluble in water. One exception is beryllium difluoride. In addition, many transition metal difluorides are water-soluble.
Calcium difluoride is a notable compound. In the form of the mineral fluorite it is the major source of commercial fluorine. It also has an epynomic crystal structure, which is an end member of the spectrum starting from bixbyite and progressing through pyrochlore.
:{| class="wikitable sortable" |+ Solubility-related constants of alkaline earth metal fluorides ! Metal
! M HE ! F HE ! "MF" unit
HE ! MF lattice
energies (−kJ/mol) ! Solubility
(mol/L) |- | Be | 2,455 | 458 | 3,371 | 3,526 | soluble |- | Mg | 1,922 | 458 | 2,838 | 2,978 | 0.0012 |- | Ca | 1,577 | 458 | 2,493 | 2,651 | 0.0002 |- | Sr | 1,415 | 458 | 2,331 | 2,513 | 0.0008 |- | Ba | 1,361 | 458 | 2,277 | 2,373 | 0.006 |}
Usage examples of "difluoride".
Polyvinylidene difluoride was a special polymer in that respect—carbon atoms were linked to hydrogen and fluorine atoms in such a way that the resulting substance was even more piezoelectric than quartz.