This bar chart shows how many different oxidation states each element can exhibit in compounds. Some elements show only one state, while others display remarkable versatility.

Manganese and osmium lead with the most oxidation states (−3 to +7 for Mn), reflecting their multiple accessible d-electrons. Transition metals generally show the most variety due to close energy spacing of d-orbitals. This variability explains why transition metals are essential catalysts - they can shuttle between states to facilitate electron transfer reactions.