Answer: K, F (Potassium, Fluorine)
Explanation: Ionic bonds are formed by transfer of electrons between metal and non metals.
Covalent bonds are formed by sharing of electrons between non metals.
Electronic configuration of potassium:
\([K]:19:1s^22s^22p^63s^23p^64s^1\)
Potassium atom will lose one electron to gain noble gas configuration and form \(K^+\).
\([K^{+}]:18:1s^22s^22p^63s^23p^6\)
Electronic configuration of fluorine:
\([F]:9:1s^22s^22p^5\)
Fluorine atom will gain one electron to gain noble gas configuration and form \(F^-\).
\([F^-]:10:1s^22s^22p^6\)
In potassium fluoride the one electron from potassium metal gets transferred to fluorine atom and thus form an ionic bond to give \(KF\)
