What is the hybridisation and the geometry of the amines?

Options

A. `SP2` hybridised and pyramidal geometry
B. `SP3` hybridised and planar geometry
C. `SP2` hybridised and planar geometry
D. `SP3` hybridised and pyramidal geometry

Answer

To determine the hybridization and geometry of amines, we can follow these steps:

### Step 1: Identify the Structure of Amines
Amines are organic compounds that contain nitrogen. The simplest amine is ammonia (NH₃), which has one nitrogen atom bonded to three hydrogen atoms.

### Step 2: Count the Electron Domains
In the case of ammonia (NH₃):
- The nitrogen atom has three hydrogen atoms bonded to it (3 bond pairs).
- There is also one lone pair of electrons on the nitrogen atom.

### Step 3: Determine the Total Number of Electron Domains
The total number of electron domains around the nitrogen atom is:
- 3 bond pairs (from the N-H bonds)
- 1 lone pair

Thus, the total number of electron domains is 4.

### Step 4: Determine the Hybridization
The hybridization can be determined using the formula:
- Number of hybrid orbitals = Number of electron domains

Since there are 4 electron domains, the hybridization of nitrogen in amines is:
- **SP³ hybridization** (because 4 hybrid orbitals are formed).

### Step 5: Determine the Geometry
The presence of a lone pair affects the geometry:
- With 4 electron domains, the ideal geometry is tetrahedral.
- However, the lone pair occupies more space and repels the bond pairs, resulting in a different shape.

Thus, the geometry of amines is:
- **Pyramidal geometry** (due to the lone pair).

### Conclusion
The hybridization of amines is **SP³**, and the geometry is **pyramidal**.

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