Question

Predict the approximate bond angles for

1. The C-N-C bond angle in(CH₃)₂ NH₂⁺.
2. The C-N-H bond angle in CH₃CH₂NH₂.
3. The H-C-N bond angle in(CH₃)₂NH.
4. The H-C-O bond angle in CH₃OCH₃.

Short answer

a. 109.5⁰

b. 107.3⁰

c. 109.5⁰

d. 109.5⁰

Step-by-step solution

Find out hybridisation of central atom

a. The central nitrogen atom is sp³hybridised as it forms only a single bond and does not have a lone pair.

b. The central nitrogen atom is sp³ hybridised as it is forming three single bonds and has one lone pair.

c. The central carbon atom is sp³hybridised as it forms three single bonds with three hydrogen atoms and one single bond with a nitrogen atom and does not have a lone pair.

d. The central carbon atom is sp³hybridised as it is bonded to 3 hydrogen atoms and an oxygen atom by single bonds. It does not have a lone pair.

Finding the respective bond angle.

a. The C-N-C bond angle in(CH₃)₂NH₂⁺.

As the central atom is sp³ hybridised it has a tetrahedral geometry and has no lone pair, thus the bond angle is 109.5⁰

b. The C-N-H bond angle in CH₃CH₂NH₂.

The expected geometry is tetrahedral but the presence of one lone pairs disturbs the geometry so the bond angle decreases to 107.3⁰

c. The H-C-N bond angle in (CH₃)₂NH.

As the central atom is sp³ hybridised it has a tetrahedral geometry and has no lone pair, thus the bond angle is 109.5⁰

d. The H-C-O bond angle in CH₃OCH₃.

As the central atom is sp³hybridised it has a tetrahedral geometry and has no lone pair, thus the bond angle is 109.5⁰