The catalytic conversion of methane and light alkanes into energy, liquid fuels and chemicals via reforming, dehydrogenation, partial oxidation and combustion processes occur through similar elementary C-H and O2 bond activation steps which differ only in the nature of the active sites and the surface coverages that result under operating conditions. The prevailing chemistry is ultimately controlled by the nature of the metal, the as well as the surface coverage and reactivity of chemisorbed oxygen. Experimental results for the partial oxidation of methane over supported metal clusters, for example, reveal the presence of different kinetic regimes which can be described by unique rate expressions that result for the conversion over bare and oxygen-covered metal surfaces. First-principle density functional theoretical calculations and kinetic Monte Carlo simulation are used here to elucidate the elementary C-H and O2 activation steps at different surface sites and to establish the influence of surface coverage on the catalytic activity and selectivity for the over different transition metal surfaces. The results are used to understand the partial oxidation of methane and dehydrogenation of propane and cyclohexane on transition metal particles.