Which of the following pairs of compounds has the same molecular shapes?
a) AlCl3 and BF3 b) AlCl3 and PCl3 c) BF3 and NF3 d) CO2 and SO2
What's your problem here.
Bf3 and nh3
A
To determine which pairs of compounds have the same molecular shapes, we need to consider the number of electron groups around the central atom and their arrangement.
Let's analyze each pair of compounds:
a) AlCl3 and BF3:
- AlCl3 has one aluminum atom bonded to three chlorine atoms. Since aluminum has three valence electrons and chlorine has seven, the molecule has a total of 26 valence electrons. Based on VSEPR theory (Valence Shell Electron Pair Repulsion theory), we can predict that AlCl3 has a trigonal planar molecular shape.
- BF3 has one boron atom bonded to three fluorine atoms. Since boron has three valence electrons and fluorine has seven, the molecule has a total of 24 valence electrons. According to VSEPR theory, BF3 also has a trigonal planar molecular shape.
So, option a) AlCl3 and BF3 have the same molecular shape.
b) AlCl3 and PCl3:
- We have already determined that AlCl3 has a trigonal planar shape.
- PCl3 has one phosphorus atom bonded to three chlorine atoms. Since phosphorus has five valence electrons and chlorine has seven, the molecule has a total of 26 valence electrons. According to VSEPR theory, PCl3 has a trigonal pyramidal molecular shape.
Therefore, option b) AlCl3 and PCl3 do not have the same molecular shape.
c) BF3 and NF3:
- We have already determined that BF3 has a trigonal planar shape.
- NF3 has one nitrogen atom bonded to three fluorine atoms. Since nitrogen has five valence electrons and fluorine has seven, the molecule has a total of 26 valence electrons. Based on VSEPR theory, NF3 has a trigonal pyramidal molecular shape.
Thus, option c) BF3 and NF3 do not have the same molecular shape.
d) CO2 and SO2:
- CO2 has one carbon atom double-bonded to two oxygen atoms. Since carbon has four valence electrons, and oxygen has six, the molecule has a total of 16 valence electrons. Based on VSEPR theory, CO2 has a linear molecular shape.
- SO2 has one sulfur atom double-bonded to two oxygen atoms. Since sulfur has six valence electrons and oxygen has six, the molecule has a total of 18 valence electrons. According to VSEPR theory, SO2 has a bent molecular shape.
Therefore, option d) CO2 and SO2 do not have the same molecular shape.
In conclusion, the correct answer is option a) AlCl3 and BF3. Both of these compounds have a trigonal planar molecular shape.