What is the bond angle in cumulene (C4H4), of the C=C=C bond and the H-C-H bonds?

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Answer 1 · 2015-12-23T22:38:09

The $"C=C=C"$ bond angle is 180°, and the $"H-C-H"$ bond angle is 120 °.

The structure of cumulene is

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The $bb"C=C=C"$ bond angles

The internal carbon atoms are each directly bonded to two other carbon atoms, so they are each $"AX"_2$ systems.

According to VSEPR theory, the bond angle in an $"AX"_2$ system is 180 °

The $bb"H-C-H"$ bond angles

Each carbon atom is directly bonded to three other carbon atoms ( $"C, H"$ , and $"H"$ ), so they are each $"AX"_3$ systems.

According to VSEPR theory, the bond angle in an $"AX"_3$ system is 120 °