Krypton is a group 18 element which is one of the 6 noble gases. These noble gases are known for being inert, which suggests that they will not react with other elements or form new compounds due to having full valence shells already. However, it turns out that Krypton can form bonds to very electronegative elements. The most electronegative element, which does have a tendency to react with Krypton is Fluorine and the reaction is shown below:
Kr (g) + F2 (g) --> KrF2 (g)
