2. Which of the following molecules is/are trigonal pyramidal?
N2O
NH3
C2H2
SiF4
HN3
HCN
SO3
H2S
CF4
PF3
H2O
BF3
COS
O3
SO2
CS2
AsH3
AsH3
To determine which of the following molecules are trigonal pyramidal, you need to assess their molecular geometries.
The molecular geometry is determined by the arrangement of the atoms around the central atom and the number of bonding and non-bonding electron pairs.
In a trigonal pyramidal molecule, the central atom is bonded to three other atoms and has one lone pair of electrons. The arrangement of these atoms and electron pairs gives rise to a pyramid-like shape.
Let's go through each of the molecules and assess their molecular geometries:
1. N2O: This molecule has a linear geometry, not trigonal pyramidal.
2. NH3: This molecule has a trigonal pyramidal geometry. The central nitrogen atom is bonded to three hydrogen atoms and has one lone pair of electrons.
3. C2H2: This molecule has a linear geometry, not trigonal pyramidal.
4. SiF4: This molecule has a tetrahedral geometry. The central silicon atom is bonded to four fluorine atoms, but it has no lone pairs of electrons.
5. HN3: This molecule has a trigonal pyramidal geometry. The central nitrogen atom is bonded to three hydrogen atoms and has one lone pair of electrons.
6. HCN: This molecule has a linear geometry, not trigonal pyramidal.
7. SO3: This molecule has a trigonal planar geometry, not trigonal pyramidal.
8. H2S: This molecule has a bent geometry, not trigonal pyramidal.
9. CF4: This molecule has a tetrahedral geometry, not trigonal pyramidal.
10. PF3: This molecule has a trigonal pyramidal geometry. The central phosphorus atom is bonded to three fluorine atoms and has one lone pair of electrons.
11. H2O: This molecule has a bent geometry, not trigonal pyramidal.
12. BF3: This molecule has a trigonal planar geometry, not trigonal pyramidal.
13. COS: This molecule has a linear geometry, not trigonal pyramidal.
14. O3: This molecule has a bent geometry, not trigonal pyramidal.
15. SO2: This molecule has a bent geometry, not trigonal pyramidal.
16. CS2: This molecule has a linear geometry, not trigonal pyramidal.
17. AsH3: This molecule has a trigonal pyramidal geometry. The central arsenic atom is bonded to three hydrogen atoms and has one lone pair of electrons.
Therefore, the molecules NH3, HN3, PF3, and AsH3 are the molecules that are trigonal pyramidal.