Question

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

Answer 1

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

Explanation:

The structure of cumulene is

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 °