VSEPR Practice Problems | PDF - Free Printable

The task involves solving VSEPR (Valence Shell Electron Pair Repulsion) practice problems. The goal is to:

1. Draw the 2-D Lewis structure for each molecule or ion.
2. Determine both the electron geometry (ED) and the molecular geometry.

Steps to Solve:

1. Draw the Lewis Structure:
- Calculate the total number of valence electrons.
- Place the central atom in the center and surrounding atoms around it.
- Distribute electrons to satisfy the octet rule (or duet rule for hydrogen).
- Ensure all atoms have a complete outer shell, using lone pairs if necessary.

2. Determine the Electron Geometry:
- Count the total number of electron pairs (both bonding and lone pairs) around the central atom.
- Use the VSEPR theory to determine the electron geometry based on the number of electron pairs:
- 2 pairs: Linear
- 3 pairs: Trigonal planar
- 4 pairs: Tetrahedral
- 5 pairs: Trigonal bipyramidal
- 6 pairs: Octahedral

3. Determine the Molecular Geometry:
- Consider only the positions of the atoms (not the lone pairs) to determine the molecular geometry.
- Lone pairs affect the shape but are not included in the molecular geometry description.

---

Example Solution for One Molecule: \( \text{PF}_3 \)

#### Step 1: Draw the Lewis Structure
- Phosphorus (P) is the central atom.
- Total valence electrons:
- P: 5
- F: 7 × 3 = 21
- Total = 5 + 21 = 26
- Place P in the center and F atoms around it.
- Form single bonds between P and each F atom.
- Distribute remaining electrons as lone pairs on F atoms to satisfy the octet rule.
- Final Lewis structure:
```
F
|
F---P---F
|
F
```

#### Step 2: Determine Electron Geometry
- Central atom (P) has 4 regions of electron density: 3 bonding pairs and 1 lone pair.
- Electron geometry: Tetrahedral.

#### Step 3: Determine Molecular Geometry
- Ignore the lone pair when determining the molecular geometry.
- The three F atoms form a trigonal pyramidal shape.
- Molecular geometry: Trigonal pyramidal.

---

General Solutions for All Molecules

Below are the solutions for all molecules listed in the problem. Due to space constraints, I will summarize the results without detailed Lewis structures.

---

#### 1. \( \text{PF}_3 \)
- Lewis Structure: Central P with 3 F atoms and 1 lone pair.
- Electron Geometry: Tetrahedral
- Molecular Geometry: Trigonal pyramidal

#### 2. \( \text{PF}_5 \)
- Lewis Structure: Central P with 5 F atoms.
- Electron Geometry: Trigonal bipyramidal
- Molecular Geometry: Trigonal bipyramidal

#### 3. \( \text{SF}_4 \)
- Lewis Structure: Central S with 4 F atoms and 1 lone pair.
- Electron Geometry: Trigonal bipyramidal
- Molecular Geometry: See-saw

#### 4. \( \text{SF}_6 \)
- Lewis Structure: Central S with 6 F atoms.
- Electron Geometry: Octahedral
- Molecular Geometry: Octahedral

#### 5. \( \text{CH}_3^+ \)
- Lewis Structure: Central C with 3 H atoms and no lone pairs.
- Electron Geometry: Trigonal planar
- Molecular Geometry: Trigonal planar

#### 6. \( \text{ClO}^- \)
- Lewis Structure: Central Cl with 1 O atom and 2 lone pairs.
- Electron Geometry: Tetrahedral
- Molecular Geometry: Bent (angular)

#### 7. \( \text{ClO}_2^- \)
- Lewis Structure: Central Cl with 2 O atoms and 2 lone pairs.
- Electron Geometry: Tetrahedral
- Molecular Geometry: Bent (V-shaped)

#### 8. \( \text{ClO}_3^- \)
- Lewis Structure: Central Cl with 3 O atoms and 1 lone pair.
- Electron Geometry: Tetrahedral
- Molecular Geometry: Trigonal pyramidal

#### 9. \( \text{ClO}_4^- \)
- Lewis Structure: Central Cl with 4 O atoms.
- Electron Geometry: Tetrahedral
- Molecular Geometry: Tetrahedral

#### 10. \( \text{KrF}_2 \)
- Lewis Structure: Central Kr with 2 F atoms and 3 lone pairs.
- Electron Geometry: Linear
- Molecular Geometry: Linear

#### 11. \( \text{XeF}_4 \)
- Lewis Structure: Central Xe with 4 F atoms and 2 lone pairs.
- Electron Geometry: Octahedral
- Molecular Geometry: Square planar

#### 12. \( \text{XeF}_6 \)
- Lewis Structure: Central Xe with 6 F atoms.
- Electron Geometry: Octahedral
- Molecular Geometry: Octahedral

#### 13. \( \text{XeO}_3 \)
- Lewis Structure: Central Xe with 3 O atoms and 2 lone pairs.
- Electron Geometry: Tetrahedral
- Molecular Geometry: Trigonal pyramidal

#### 14. \( \text{XeO}_2\text{F}_2 \)
- Lewis Structure: Central Xe with 2 O atoms, 2 F atoms, and 2 lone pairs.
- Electron Geometry: Tetrahedral
- Molecular Geometry: Square planar

#### 15. \( \text{CS}_2 \)
- Lewis Structure: Central C with 2 S atoms.
- Electron Geometry: Linear
- Molecular Geometry: Linear

#### 16. \( \text{NO}_3^- \)
- Lewis Structure: Central N with 3 O atoms.
- Electron Geometry: Trigonal planar
- Molecular Geometry: Trigonal planar

#### 17. \( \text{CO}_3^{2-} \)
- Lewis Structure: Central C with 3 O atoms.
- Electron Geometry: Trigonal planar
- Molecular Geometry: Trigonal planar

#### 18. \( \text{BH}_3 \)
- Lewis Structure: Central B with 3 H atoms.
- Electron Geometry: Trigonal planar
- Molecular Geometry: Trigonal planar

#### 19. \( \text{XeF}_3^+ \)
- Lewis Structure: Central Xe with 3 F atoms and 2 lone pairs.
- Electron Geometry: Trigonal bipyramidal
- Molecular Geometry: T-shaped

#### 20. \( \text{BrF}_3 \)
- Lewis Structure: Central Br with 3 F atoms and 2 lone pairs.
- Electron Geometry: Trigonal bipyramidal
- Molecular Geometry: T-shaped

#### 21. \( \text{IF}_5 \)
- Lewis Structure: Central I with 5 F atoms and 1 lone pair.
- Electron Geometry: Octahedral
- Molecular Geometry: Square pyramidal

#### 22. \( \text{HCN} \)
- Lewis Structure: Linear arrangement with H, C, and N.
- Electron Geometry: Linear
- Molecular Geometry: Linear

#### 23. \( \text{NH}_3\text{Cl}^+ \)
- Lewis Structure: Central N with 3 H atoms and 1 Cl atom.
- Electron Geometry: Tetrahedral
- Molecular Geometry: Tetrahedral

#### 24. \( \text{I}_3^- \)
- Lewis Structure: Linear arrangement with I-I-I and lone pairs.
- Electron Geometry: Linear
- Molecular Geometry: Linear

#### 25. \( \text{N}_3^- \)
- Lewis Structure: Linear arrangement with N-N-N and lone pairs.
- Electron Geometry: Linear
- Molecular Geometry: Linear

---

Final Answer:

\[
\boxed{
\begin{array}{ll}
\text{1. PF}_3 & \text{Trigonal pyramidal} \\
\text{2. PF}_5 & \text{Trigonal bipyramidal} \\
\text{3. SF}_4 & \text{See-saw} \\
\text{4. SF}_6 & \text{Octahedral} \\
\text{5. CH}_3^+ & \text{Trigonal planar} \\
\text{6. ClO}^- & \text{Bent} \\
\text{7. ClO}_2^- & \text{Bent} \\
\text{8. ClO}_3^- & \text{Trigonal pyramidal} \\
\text{9. ClO}_4^- & \text{Tetrahedral} \\
\text{10. KrF}_2 & \text{Linear} \\
\text{11. XeF}_4 & \text{Square planar} \\
\text{12. XeF}_6 & \text{Octahedral} \\
\text{13. XeO}_3 & \text{Trigonal pyramidal} \\
\text{14. XeO}_2\text{F}_2 & \text{Square planar} \\
\text{15. CS}_2 & \text{Linear} \\
\text{16. NO}_3^- & \text{Trigonal planar} \\
\text{17. CO}_3^{2-} & \text{Trigonal planar} \\
\text{18. BH}_3 & \text{Trigonal planar} \\
\text{19. XeF}_3^+ & \text{T-shaped} \\
\text{20. BrF}_3 & \text{T-shaped} \\
\text{21. IF}_5 & \text{Square pyramidal} \\
\text{22. HCN} & \text{Linear} \\
\text{23. NH}_3\text{Cl}^+ & \text{Tetrahedral} \\
\text{24. I}_3^- & \text{Linear} \\
\text{25. N}_3^- & \text{Linear} \\
\end{array}
}
\]