Question

question 25 (1 point)
ch₄ molecule has ____ type of electron geometry and ____ type of molecular geometry.

1. trigonal pyramid, trigonal pyramid
2. tetrahedral, trigonal (triangular) pyramid
3. tetrahedral, tetrahedral
4. tetrahedral, trigonal planar

Explanation:

To determine the electron and molecular geometry of \( \text{CH}_4 \) (methane), we analyze its structure:

• Electron Geometry: The central carbon atom in \( \text{CH}_4 \) has 4 bonding pairs (no lone pairs) of electrons. According to VSEPR theory, 4 bonding regions correspond to a tetrahedral electron geometry.
• Molecular Geometry: Since there are no lone pairs on the central atom, the molecular geometry (shape) is determined solely by the bonding pairs. For 4 bonding pairs with no lone pairs, the molecular geometry is also tetrahedral.

Now, we evaluate the options:

1. Trigonal Pyramid (incorrect, as \( \text{CH}_4 \) has no lone pairs to form a trigonal pyramid).
2. Tetrahedral (electron) and Trigonal Pyramid (molecular) (incorrect, molecular geometry is tetrahedral, not trigonal pyramid).
3. Tetrahedral, Tetrahedral (matches both electron and molecular geometry).
4. Tetrahedral (electron) and Trigonal Planar (molecular) (incorrect, trigonal planar applies to 3 bonding pairs, not 4).

Answer:

1. Tetrahedral, Tetrahedral