# Chlorine Fluoride, why not Fluorine Chloride

Why is Chlorine Fluoride called "Chlorine Fluoride" rather than "Fluorine Chloride"? As I was taught in school that normally that when nonmetal combine with nonmetal then we write the compound with lower atomic number first.

• Think about electronegativities. – Equinox Jun 5 '17 at 19:21
• Anionic part is written in the suffix. – chail10 Jun 6 '17 at 0:40

Regarding $\ce{ClF}$, fluorine is clearly the electronegative atom here. Thus the name would be Chlorine fluoride.
Another example of this is from my personal favorite compound, $\ce{O2F2}$
$\ce{O2F2}$ would be correctly called as Dioxygen difluoride.