Chemistry

Dichromate ions contain peroxide-like oxygen bridges, but the key is recognizing that $\text{Cr}_2\text{O}_7^{2-}$ has a structure where two chromium atoms are connected through oxygen atoms, not directly to each other. Count the oxygens bonded to chromium and identify which oxygens are bonded to each other rather than just to metal centers—this requires visualizing the actual bridging geometry of the dichromate ion.

Dichromate ions contain peroxide-like oxygen bridges, but the key is recognizing that $\text{Cr}_2\text{O}_7^{2-}$ has a structure where two chromium atoms are connected through oxygen atoms, not directly to each other. Count the oxygens bonded to chromium and identify which oxygens are bonded to each other rather than just to metal centers—this requires visualizing the actual bridging geometry of the dichromate ion.