What Shape Does PCl5 Have?

PCl5 has a Trigonal bipyramidal molecular geometry (AX5, trigonal bipyramidal) with a bond angle of 90° (axial–equatorial), 120° (equatorial–equatorial), 180° (axial–axial). The central phosphorus carries 5 bonding domain(s) and 0 lone pair(s) — 5 electron domains in total. The axial bonds are slightly longer and more reactive than the equatorial set — two distinct bond families in one molecule.

Hybridisation is conventionally described as sp3d (hypervalent: ten electrons around P). Polarity: Nonpolar overall (symmetric).

1. Molecular Identity and Key Parameters

Molar mass is the average value rounded for procurement use. Hybridisation labels are the conventional VSEPR-level description; orbital treatment becomes more nuanced at higher levels of theory.

2. Drawing the Lewis Structure of PCl5, Step by Step

1. Count valence electrons: 5 (P) + 5×7 (Cl) = 40 — a total of 40 electrons (20 pairs) must be placed.
2. Build the skeleton: place the phosphorus at the centre and attach the terminal atoms with single bonds; hydrogen is never a central atom. Each single bond consumes 2 electrons.
3. Complete terminal octets: distribute the remaining electrons as lone pairs on the terminal atoms first (hydrogens already carry their duet from the single bond).
4. Satisfy the central atom: Five P–Cl bonds — three equatorial (120° apart) and two axial (perpendicular to that plane); no lone pairs.
5. Verify: Phosphorus exceeds the octet; period 3 accommodates the expanded valence shell. Apply the standard formal-charge check (valence − nonbonding − half of bonding electrons) to confirm the drawn form.

A worked diagram of this molecule is kept in the companion guide: PCl5 Lewis structure.

3. VSEPR Analysis: Why PCl5 Is trigonal bipyramidal

VSEPR theory counts electron domains — every σ bond counts once regardless of bond order, and every lone pair counts once. PCl5 has 5 such domains around the phosphorus: 5 bonding and 0 lone. 5 domains correspond to a trigonal bipyramidal electron-domain arrangement; with no lone pair to hide the observed molecular shape is trigonal bipyramidal (AX5).

Bond angle: 90° (axial–equatorial), 120° (equatorial–equatorial), 180° (axial–axial) because the axial bonds are slightly longer and more reactive than the equatorial set — two distinct bond families in one molecule.

Polarity: Nonpolar overall (symmetric).

4. The Most Common Mistake When Drawing PCl5

5. Why the Geometry Matters in Practice

Chlorinating and dehydrating reagent; in the solid state it ionises to [PCl4]+[PCl6]−, an identity note that belongs on any high-purity specification.

Structure-level identity is exactly what a purchase order has to fix: the same molecular formula can hide isomers, hydrates or salt forms with different handling profiles. Before ordering, match CAS (10026-13-8), assay, water content and container rating against the datasheet, and request the COA batch that will ship.

Compare Phosphorus Pentachloride (PCl5) supply offers →

6. Quick FAQs on PCl5

7. References

1. IUPAC / Gillespie, Assessment of the VSEPR model. Basis of AXE notation and lone-pair ordering. VSEPR entry
2. PubChem compound record for Phosphorus Pentachloride (PCl5). Registry number, formula and computed descriptors. PubChem 10026-13-8
3. Companion Lewis-structure guide on this site. Worked diagram for PCl5. Lewis structure PCl5