Although they were formerly called the inert gases, at least the heavier elements of Group 8 do form relatively stable compounds. For example, xenon combines directly with elemental fluorine at elevated temperatures in the presence of a nickel catalyst. Use table 1 and table 2. Xe(g) + 2 F2(g) → XeF4(s) What is the theoretical mass of xenon tetrafluoride that should form when 163 g of xenon is reacted with 164 g of F2? g= What is the percent yield if only 156 g of XeF4 is actually isolated?