Determine the electron geometry of the nitrogen atom within methylamine, CH₃NH₂.  

A. Linear
B. Trigonal Pyramidal
C. Tetrahedral
D. Trigonal Planar

• A. Linear
• B. Trigonal Pyramidal
• C. Tetrahedral
• D. Trigonal Planar

Answer: (C)

Verified step by step guidance

1. Identify the central atom in the molecule. In methylamine (CH3NH2), the nitrogen (N) atom is the central atom for the NH2 group.
2. Count the number of electron groups around the nitrogen atom. Electron groups include bonds (single, double, or triple) and lone pairs of electrons. In this case, nitrogen is bonded to two hydrogen atoms and has one lone pair of electrons.
3. Determine the total number of electron groups around the nitrogen atom. There are two N-H bonds and one lone pair, making a total of three electron groups.
4. Use the VSEPR (Valence Shell Electron Pair Repulsion) theory to determine the electron geometry. According to VSEPR theory, three electron groups around a central atom result in a trigonal planar electron geometry.
5. Consider the effect of the lone pair on the molecular shape. While the electron geometry is trigonal planar, the presence of a lone pair changes the molecular shape to trigonal pyramidal.