Question

Predict the approximate bond angle in

1. The methyl cation
2. The methyl radical
3. The methyl anion

Short answer

1. 120⁰
2. 120⁰
3. 109⁰

Step-by-step solution

Subpart (a) The methyl cation.

One s-orbital and two p orbitals combine to form three sp² hybrid orbitals that form three covalent bonds in methyl cation. The positively charged carbon lies in a plane and the unhybridized p-orbital lies perpendicular to the plane. The bond angle for sp²hybridized carbon is 120⁰ .

Subpart (b) The methyl radical.

One s-orbital and two p orbitals combine to form three sp² hybrid orbitals that form three covalent bonds in methyl radical. The extra electron in methyl radical resides in the p orbital with distributed electron density. The carbon in methyl radical is also sp² hybridized and so the bond angle is 120⁰.

Subpart (c) The methyl anion.

Three bonding electron pairs and one lone pair electron makes up the methyl anion. The negatively charged carbon atom in methyl anion is sp² hybridised. 3 sp³ orbitals of the carbon overlap with s orbitals of hydrogen while one sp³orbital holds the lone pair forming a bond angle of 109⁰ .