VSEPR worksheet for determining bonding pairs, lone pairs, and molecular shapes of molecules.

Let’s go step by step for each molecule. We’ll count:

- Bonding pairs: Each line (single, double, or triple bond) counts as 1 bonding pair — even if it’s a double bond, in VSEPR we treat the whole bond as one “region” of electron density.
- Lone pairs: Dots on the central atom that are not involved in bonding.
- Molecular shape: Based on total electron domains (bonding + lone pairs), then adjust for lone pairs to get molecular geometry.

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1. NCl₃ (Nitrogen trichloride)

Central atom: N
N has 5 valence electrons.
Each Cl forms 1 single bond → 3 bonding pairs.
Remaining electrons on N: 5 - 3 = 2 → that’s 1 lone pair.

Total electron domains: 3 bonding + 1 lone = 4 → tetrahedral electron geometry
But molecular shape ignores lone pairs → trigonal pyramidal

✔ Bonding pairs: 3
✔ Lone pairs: 1
✔ Molecular Shape: Trigonal Pyramidal

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2. BCl₃ (Boron trichloride)

Central atom: B
B has 3 valence electrons.
Forms 3 single bonds with Cl → 3 bonding pairs.
No leftover electrons → 0 lone pairs.

Total electron domains: 3 → trigonal planar electron and molecular geometry.

✔ Bonding pairs: 3
✔ Lone pairs: 0
✔ Molecular Shape: Trigonal Planar

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3. [ClF₄]⁻ (Tetrafluorochlorate ion)

Central atom: Cl
Cl has 7 valence electrons.
Plus 1 extra from negative charge → 8 total.
Forms 4 single bonds with F → uses 4 electrons → 4 bonding pairs.
Leftover: 8 - 4 = 4 electrons → 2 lone pairs.

Total electron domains: 4 bonding + 2 lone = 6 → octahedral electron geometry
With 2 lone pairs opposite each other → square planar molecular shape.

✔ Bonding pairs: 4
✔ Lone pairs: 2
✔ Molecular Shape: Square Planar

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4. [NO₃]⁻ (Nitrate ion)

Central atom: N
Structure shown: One double bond to O, two single bonds to O (resonance, but for VSEPR we count regions).

In VSEPR, double bond still counts as 1 region. So:

- 3 atoms bonded to N → 3 bonding regions (even though one is double bond)
- No lone pairs on N? Let’s check:

N has 5 valence electrons.
In Lewis structure:
- Double bond to one O: uses 4 electrons (but shared)
- Two single bonds to O⁻: each uses 2 electrons (shared)
Total electrons around N: 8 (octet) → no lone pairs.

Actually, formal charge: N has +1, but in terms of electron domains: 3 bonding regions, 0 lone pairs.

Total electron domains: 3 → trigonal planar

✔ Bonding pairs: 3
✔ Lone pairs: 0
✔ Molecular Shape: Trigonal Planar

*(Note: Even though there’s resonance and charges, VSEPR only cares about number of electron domains around central atom.)*

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5. CF₄ (Carbon tetrafluoride)

Central atom: C
C has 4 valence electrons.
Forms 4 single bonds with F → 4 bonding pairs.
No leftover electrons → 0 lone pairs.

Total electron domains: 4 → tetrahedral

✔ Bonding pairs: 4
✔ Lone pairs: 0
✔ Molecular Shape: Tetrahedral

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6. [XeCl₆]²⁺ (Hexachloroxenate(II) ion)

Central atom: Xe
Xe has 8 valence electrons.
Charge is 2+ → remove 2 electrons → 6 left.
Forms 6 single bonds with Cl → uses 6 electrons → 6 bonding pairs.
Leftover: 6 - 6 = 0 → 0 lone pairs.

Wait — let’s double-check:

Xe normally has 8 valence e⁻.
In [XeCl]²⁺, total valence electrons:

Xe: 8
6 × Cl: 6×7 = 42
Minus 2 for 2+ charge → total = 8 + 42 - 2 = 48 electrons.

Now assign:

Each Cl needs 8 electrons → 6 Cl × 8 = 48 electrons.
But each bond is shared → so 6 bonds use 12 electrons (6×2).
Remaining electrons: 48 - 12 = 36 → these go to Cl atoms as lone pairs (each Cl gets 3 lone pairs → 6×6=36). Perfect.

So Xe has 6 bonding pairs, 0 lone pairs.

Total electron domains: 6 → octahedral

✔ Bonding pairs: 6
✔ Lone pairs: 0
✔ Molecular Shape: Octahedral

*(Note: Some might think Xe can’t have 6 bonds, but in ions like this, expanded octets are allowed for period 3+ elements.)*

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## Final Answer:

| LEWIS STRUCTURES | No of bonding pairs | No of lone pairs | Molecular Shape |
|---------------------------|---------------------|------------------|------------------------|
| NCl₃ | 3 | 1 | Trigonal Pyramidal |
| BCl₃ | 3 | 0 | Trigonal Planar |
| [ClF₄]⁻ | 4 | 2 | Square Planar |
| [NO₃]⁻ | 3 | 0 | Trigonal Planar |
| CF₄ | 4 | 0 | Tetrahedral |
| [XeCl]²⁺ | 6 | 0 | Octahedral |