Final answer:
In CH2CHCH3, using VSEPR theory, the molecular geometry around the first and last carbon atoms is tetrahedral, and the geometry around the middle carbon atom is trigonal planar.
Step-by-step explanation:
Using VSEPR theory, we can determine the molecular geometry around each carbon atom in CH2CHCH3. First, we identify the number of electron groups around each carbon atom. The first carbon (as you move from left to right in the molecule) is bonded to three hydrogen atoms and one carbon atom, with no lone pairs, indicating that it has a tetrahedral electron-pair geometry and thus a tetrahedral molecular geometry.
The middle carbon atom is double-bonded to another carbon and single-bonded to the first carbon, meaning it has three electron groups with no lone pairs. These groups are organized in a trigonal planar fashion as all groups are bonding pairs.
Lastly, the final carbon atom is also tetrahedral because it is bound to three hydrogen atoms and the double-bonded carbon, again with no lone pairs.
The molecular geometries around the carbon atoms in CH2CHCH3 are therefore tetrahedral for the first and last carbon atoms and trigonal planar for the middle carbon atom.