 Teflon

Teflon is a trade name strongly associated with polytetrafluoroethylene, whose repeat unit is $-\mathrm{C}{\mathrm{F}}_2-\mathrm{C}{\mathrm{F}}_2-$. The fluorinated chain gives the polymer a low-energy surface and high chemical resistance in many conditions.

Its familiar low-friction and nonwetting behavior belongs to a material surface, not to a free fluorine atom. Product formulations and other fluoropolymers sold under the same brand context should be specified separately when material identity matters.