In trimethylamine, the nitrogen has a pyramidal geometry whereas in trisilylamine `N(SiH_(3)) _(3),` it has a planar geometry. What is the reaons behind this ?

Explanation

To understand the difference in geometry between trimethylamine and trisilylamine, let's break down the reasoning step by step.

### Step 1: Identify the Structure of Trimethylamine
- **Trimethylamine (N(CH₃)₃)** consists of a nitrogen atom bonded to three methyl groups (CH₃).
- Nitrogen has 5 valence electrons, and each methyl group contributes 1 electron for bonding.

### Step 2: Determine the Electron Pair Geometry
- In trimethylamine, nitrogen forms three N-C bonds with the three methyl groups and has one lone pair of electrons.
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