The metal ions, Cm+, U+, and Tb+, and their oxides, MO+, were reacted in the gas phase with alkenes, acetonitrile, and hexafluoropropene. Product compositions and abundances provide a survey of essential aspects of the gas-phase chemistry of the curium cation, now the heaviest element for which such systematic studies have been carried out (U and Tb were included to provide comparisons). Of particular interest is the difference in behavior between the 4f lanthanide and 5f actinide series and variations in chemistry across the actinide series. The primary emphasis was on reactions with alkenes, particularly dehydrogenation, as indicative of the ability of a M+ to activate C-H bonds.(the extent of C-C activation was generally in parallel with that of C-H activation). With acetonitrile and all of the alkenes (except ethene), the three M+ ions induced dehydrogenation. Variations were evident for the different reactant substrates, but the overall qualitative ordering of dehydrogenation efficiency was U+ > Tb+ > Cm+. This order is consistent with the variation in electronic promotion energies (PE) required to provide two spin-unpaired, non-f valence electrons at the M+, i.e., a [Rg]f(n-2)d(1)s(1) configuration ("Rg" = Xe for the lanthanides and Rn for the actinides), Co enable its insertion into a C-H bond. The reduced reactivity of Cm+ relative to U+ and Tb+ suggests that the closed-shell 7s(2) electrons of ground Cm+ (S-8 [Rn]5f(7)s(2)) are ineffective in enabling C-H activation and that promotion to the D-10 [Rn]5f(7)6d(1)7s(1) configuration is prerequisite. The PE[Cm+] (48 kJ mol(-1)) is only slightly greater than PE[Tb+] (39 kJ mol(-1)) and the significantly greater reactivity of Tb+ vs Cm+ may reflect that the transition to the prepared "divalent" state (d(1)s(1)) is parity forbidden for Cm+. The three MO+ were substantially less reactive than the naked M+ but were comparably reactive to one another, consistent with a multicentered activation process, which is less efficient than direct cleavage of a C-H bond by M+ insertion. With hexafluoropropene, the primary reaction channel was F abstraction and the discrepant reactivities reflected the propensity for U to oxidize to higher valence states compared to Cm or Tb. The terminal MFn+ were. (CmF2+)-F-III, (TbF2+)-F-III, and (UF4+)-F-IV, and among the MO+, only UO+ induced F abstraction, producing UOFn+ with n = 1-3.