How can stable O2 react with other metals on earth

$O\_2$ is a molecule which has achieved a stable configuration, why then can spontaneous reactions occur between O2 and metals on earth ? Is it that stealing of electrons is preferred above sharing of electrons ?




Your question could apply to almost any reaction! All molecules have a stable electron configuration, N$\_2$, benzene, chlorophyll, proteins, DNA etc. We, humans (and all life) are *unstable* with respect to oxidation, but the fact that a reaction is exothermic (spontaneous) does not mean that it has to react quickly. Thermodynamics does not inform us about time-scales just starting and ending energies. A reaction's activation energy can be huge compared to thermal energy and in many cases it often is so reactions proceed exceedingly slowly, e.g man + O$\_2$ = CO$\_2$+H$\_2$O is, thankfully, very, very slow :)   
Note also that the heats of formation of molecules are different, so different types of molecules possess different energy and hence have the ability to react.


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