The nitrogen atom in amines is trivalent and possess an unshared pair of electrons. The geometry of trimethyl amine is
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Pyramidal
In trimethylamine (N(CH₃)₃):
- Nitrogen is sp³ hybridized.
- It forms three σ-bonds with carbon atoms and has one lone pair.
- The electron-pair geometry is tetrahedral, but due to the lone pair, the molecular geometry becomes trigonal pyramidal.
Hence, the correct option is Pyramidal.
Option 1: Tetrahedral Tetrahedral geometry occurs when all four positions are occupied by atoms (e.g., methane). Here, one position is occupied by a lone pair, so the shape is not tetrahedral.
Option 2: Pyramidal Correct. With three bonding pairs and one lone pair, the molecular shape is trigonal pyramidal. The lone pair pushes the bonded atoms downward, forming a pyramid-like structure.
Option 3: Square planar Square planar geometry requires dsp² hybridization and typically occurs in transition metal complexes. Not applicable to simple amines.
Option 4: Triangular Triangular (trigonal planar) occurs when there are three bonding pairs and no lone pair (e.g., BF₃). Here, a lone pair is present, so geometry is not planar.