Here's why:
* Potassium is a metal with the symbol K.
* Fluorine is a nonmetal with the symbol F.
* When metals and nonmetals bond, they form ionic compounds.
* In this case, potassium loses an electron to become a positively charged ion (K+), and fluorine gains an electron to become a negatively charged ion (F-).
* The opposite charges attract, forming the compound potassium fluoride (KF).
