VSEPR Table with Examples: From Linear to Octahedral

Printable VSEPR Table for Common MoleculesUnderstanding molecular shape is one of the foundations of chemistry. The Valence Shell Electron Pair Repulsion (VSEPR) model provides a straightforward way to predict molecular geometry by assuming electron domains (bonding pairs and lone pairs) around a central atom repel each other and arrange to minimize repulsion. This article explains VSEPR basics, gives a printable table of common molecular geometries, includes examples and tips for using the table, and offers a few practice problems with answers.

What VSEPR Predicts and Why It Matters

VSEPR predicts the arrangement of electron domains around a central atom and, from that, the molecular geometry (the arrangement of atoms). Geometry affects properties such as polarity, reactivity, intermolecular forces, and physical characteristics (e.g., boiling point). For example, carbon dioxide (CO2) is linear and nonpolar overall, whereas water (H2O) is bent and polar—differences that explain distinct behaviors in solvents, bonding, and biological interactions.

Basic VSEPR Rules (Concise)

• Count all electron domains (bonding pairs—each single, double, or triple bond counts as one domain—and lone pairs) around the central atom.
• Electron domains adopt geometries that minimize repulsion (maximize separation).
• Lone pairs exert greater repulsion than bonding pairs, so they slightly compress bond angles between bonding pairs.
• Multiple bonds (double/triple) act like one domain but exert slightly greater repulsion than single bonds.

Printable VSEPR Table (Common Electron-Domain Counts)

Below is a compact, printable VSEPR reference for common electron-domain counts around a central atom. Use it to quickly identify the electron-domain geometry and the molecular geometry (when lone pairs are present), typical bond angles, and brief example molecules.

How to Use the Table — Step-by-Step

1. Identify the central atom (usually the least electronegative element that isn’t hydrogen).
2. Count valence electrons for the central atom and surrounding atoms; draw a Lewis structure to determine bonds and lone pairs on the central atom.
3. Count electron domains around the central atom (single/double/triple bonds each = 1 domain; each lone pair = 1 domain).
4. Match the domain count to the electron-domain geometry and then determine the molecular geometry based on how many of those domains are lone pairs.
5. Estimate bond angles using the table and remember lone pairs compress angles slightly.

Example: For NH3, nitrogen has three bonding pairs and one lone pair = 4 domains → tetrahedral electron-domain geometry → molecular geometry is trigonal pyramidal; bond angle ≈ 107°.

Common Exceptions and Nuances

• Expanded octets: Elements in period 3 or below (e.g., P, S, Cl) can have more than eight electrons and form 5 or 6 domains (trigonal bipyramidal, octahedral).
• Electron-withdrawing substituents and differences in electronegativity can slightly distort ideal angles.
• Resonance can delocalize electron density; if the central atom’s formal lone pair is delocalized, predicted angles may shift toward values expected for fewer localized lone pairs.
• For molecules with multiple central atoms, apply VSEPR to each central atom separately.

Printable One-Page Version (Text You Can Copy)

Below is a condensed one-page text you can paste into a document to print.

Printable VSEPR Table — Common Molecules

• 2 domains — Electron-domain geometry: Linear — Molecular geometry: Linear — Bond angle: 180° — Examples: CO2, BeCl2
• 3 domains — Electron-domain geometry: Trigonal planar — Molecular geometry: Trigonal planar (0 LP) / Bent (1 LP) — Bond angle: 120° (≈117° with 1 LP) — Examples: BF3; SO2
• 4 domains — Electron-domain geometry: Tetrahedral — Molecular geometry: Tetrahedral (0 LP) / Trigonal pyramidal (1 LP) / Bent (2 LP) — Bond angle: 109.5° (≈107° with 1 LP; ≈104.5° with 2 LP) — Examples: CH4; NH3; H2O
• 5 domains — Electron-domain geometry: Trigonal bipyramidal — Molecular geometry: Trigonal bipyramidal (0 LP) / See-saw (1 LP) / T-shaped (2 LP) / Linear (3 LP) — Bond angles: 90° & 120° (modified by lone pairs) — Examples: PCl5; SF4; ClF3; I3-
• 6 domains — Electron-domain geometry: Octahedral — Molecular geometry: Octahedral (0 LP) / Square pyramidal (1 LP) / Square planar (2 LP) — Bond angle: 90° — Examples: SF6; BrF5; XeF4

Practice Problems

1. Determine the molecular geometry and approximate bond angle of ClF3.
2. Predict the shape of PO4^3− (phosphate ion) around phosphorus.
3. What is the geometry of SO2 and why does it have that shape?

Answers:

1. ClF3: 5 electron domains (3 bonding, 2 lone pairs) → T-shaped; bond angles ~90° between the bonded atoms.
2. PO4^3−: Phosphorus typically has 4 bonding domains, 0 lone pairs → tetrahedral; bond angles ≈109.5°.
3. SO2: 3 electron domains (2 bonding, 1 lone pair) → bent (trigonal planar electron-domain geometry) with bond angle slightly less than 120° due to lone pair repulsion.

Tips for Remembering Shapes

• Think of domain counts as “seats” around the central atom: 2 = line, 3 = flat triangle, 4 = tetrahedron (pyramid with triangular base), 5 = trigonal bipyramid (one triangle plus two axial positions), 6 = octahedron (like two square pyramids base-to-base).
• Lone pairs “take up more space” — visualize them as slightly bigger balloons pushing bonded atoms closer together.

Closing Note

This printable VSEPR table and quick guide should serve well for homework, lab work, or quick reference. For molecules with ambiguous electron distributions (resonance, hypervalence, or multiple central atoms), complement VSEPR with Lewis-structure practice and, if needed, molecular modeling or computational chemistry for precise geometries.