The metals at the bottom of the activity series are least reactive. They are often found in free state. E.g. Gold, silver, and copper. But copper and silver are also found in combined state as their sulphide or oxide ores. E.g. copper which is found as Cu2S in nature can be obtained from its ore by just heating in air.2Cu2S + 3O2 ------> 2Cu2O + 2SO22Cu2O + Cu2S -----> 6 Cu + SO2Similarly, cinnabar is an ore of mercury. When it is heated in air, it is first converted into mercuric oxide ( HgO). Mercuric oxide is then reduced to mercury on further heating.2HgS + 3O2 ----> 2HgO + 2SO22HgO -------> 2Hg + O2
Metals like copper, mercury, silver are less reactive.
Metals at the bottom of reactivity series can be obtained by heating their compounds.For example when cinnabar (HgS)is heated in a furnace, it is reduced to metalli8c mercury.
HgS + O2-----) Hg+SO2