Regarding the detailed internal 3D structure of the orange dichromate ion (), which of the following — d and f Block Elements Chemistry Question

💡 Solution & Explanation

The $Cr_2O_7^{2-}$ ion is composed of two tetrahedra joined at a common oxygen vertex. The six terminal $Cr-O$ bonds are equivalent due to resonance (bond length $\approx 161/163$ pm). The two bridging $Cr-O$ bonds lack this extensive resonance, making them significantly longer ($\approx 179/180$ pm). The central $Cr-O-Cr$ bond angle is distinctly bent, measuring approximately $126^\circ - 131^\circ$, entirely contradicting a linear $180^\circ$ assertion.