A. The Lewis diagram for PO(OH)3 is: The electron-pair geometry around the P atom in PO(OH)3 is . There are lone pair(s) around the central atom, so the geometry of PO(OH)3 is . B. The Lewis diagram for SeH2 is: The electron-pair geometry around the Se atom in SeH2 is . There are lone pair(s) around the central atom, so the geometry of SeH2 is . C. The Lewis diagram for NH3 is: The electron-pair geometry around the N atom in NH3 is tetrahedral . There are 1 lone pair(s) around the central atom, so the geometry of NH3 is tetrahedral . D. The Lewis diagram for BF3 is: The electron-pair geometry around the B atom in BF3 is trigonal planar . There are 0 lone pair(s) around the central atom, so the geometry of BF3 is trigonal planar . Are You Sure? An error was detected in your answer. Check for typos, miscalculations, etc. before you submit this item again.
The Correct Answer and Explanation is :
Let’s go through each molecule and correct the statements:
A. PO(OH)3 (Phosphoric Acid)
- Lewis Structure: Phosphoric acid (PO(OH)3) has a phosphorus atom at the center, bonded to three hydroxyl (OH) groups and one double-bonded oxygen (O). Phosphorus (P) is in group 15 and can expand its valence shell because it is in period 3 or higher.
- Electron-pair Geometry: The phosphorus atom forms four bonds (one double bond to an oxygen and three single bonds to hydroxyl groups). Therefore, the electron-pair geometry is tetrahedral.
- Molecular Geometry: Since there are no lone pairs on phosphorus, the molecular geometry is also tetrahedral.
Correction for A:
- The electron-pair geometry around the P atom in PO(OH)3 is tetrahedral.
- There are 0 lone pairs around the central atom, so the geometry of PO(OH)3 is tetrahedral.
B. SeH2 (Selenium Hydride)
- Lewis Structure: Selenium (Se) is in group 16 and forms two single bonds with two hydrogen atoms. Se has two lone pairs of electrons remaining after bonding with hydrogen atoms.
- Electron-pair Geometry: With two bonding pairs and two lone pairs, the electron-pair geometry around selenium is tetrahedral (considering both bonding and lone pairs).
- Molecular Geometry: Since there are lone pairs, the molecular geometry will be bent (also called “V-shaped”), as the lone pairs push the bonding pairs closer together.
Correction for B:
- The electron-pair geometry around the Se atom in SeH2 is tetrahedral.
- There are 2 lone pairs around the central atom, so the geometry of SeH2 is bent.
C. NH3 (Ammonia)
- Lewis Structure: Ammonia (NH3) has a nitrogen atom bonded to three hydrogen atoms, and nitrogen has one lone pair of electrons.
- Electron-pair Geometry: The electron-pair geometry for NH3 is tetrahedral because there are three bonding pairs and one lone pair.
- Molecular Geometry: Since there is one lone pair, the molecular geometry is trigonal pyramidal (due to the lone pair pushing down on the bonding pairs).
Correction for C:
- The electron-pair geometry around the N atom in NH3 is tetrahedral.
- There is 1 lone pair around the central atom, so the geometry of NH3 is trigonal pyramidal.
D. BF3 (Boron Trifluoride)
- Lewis Structure: Boron trifluoride (BF3) consists of a boron atom bonded to three fluorine atoms. Boron does not have a full octet, but it is an exception, as it can have only six electrons in its valence shell.
- Electron-pair Geometry: There are three bonding pairs around the boron atom, so the electron-pair geometry is trigonal planar.
- Molecular Geometry: Since there are no lone pairs on boron, the molecular geometry is also trigonal planar.
Correction for D:
- The electron-pair geometry around the B atom in BF3 is trigonal planar.
- There are 0 lone pairs around the central atom, so the geometry of BF3 is trigonal planar.
Final Correct Answers:
A. The electron-pair geometry around the P atom in PO(OH)3 is tetrahedral. There are 0 lone pairs around the central atom, so the geometry of PO(OH)3 is tetrahedral.
B. The electron-pair geometry around the Se atom in SeH2 is tetrahedral. There are 2 lone pairs around the central atom, so the geometry of SeH2 is bent.
C. The electron-pair geometry around the N atom in NH3 is tetrahedral. There is 1 lone pair around the central atom, so the geometry of NH3 is trigonal pyramidal.
D. The electron-pair geometry around the B atom in BF3 is trigonal planar. There are 0 lone pairs around the central atom, so the geometry of BF3 is trigonal planar.
This correction accounts for the lone pairs and bonding pairs to ensure accurate molecular geometries.