Probably not relevant for thrusters, but Xenon does make XeO2 and XeF6, and XeF4, and the other gases don't really do that (krypton does make KrF2)...
Probably not relevant for thrusters, but Xenon does make XeO2 and XeF6, and XeF4, and the other gases don't really do that (krypton does make KrF2)...