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Phosphorus dioxide Lewis Structure

Phosphorus dioxide Lewis structure (O2P). P–O double bond and P–O single bond. It shows a bent shape, sp2 hybridization on P, ≈119° bond angles. Count 17 valence electrons and a trigonal planar electron-domain arrangement. Polarity: Polar. Hamlin3 MIN READSeptember 30, 2026

Phosphorus dioxide Lewis Structure: O2P Lewis Structure, bent Geometry, sp2 Hybridization & Polarity

Phosphorus dioxide Lewis structure Cover

Phosphorus dioxide Key Facts

The Phosphorus dioxide Lewis structure is P–O double bond and P–O single bond; the central P has 3 electron domains (1 lone pair), giving a trigonal planar electron-domain arrangement and a bent molecular geometry with a ≈119° bond angle. P is best described as sp2-hybridized, and Phosphorus dioxide is polar because the bent shape (and/or unequal terminal atoms) prevents cancellation of the bond dipoles.

Phosphorus dioxide Lewis Structure Figure 1: Lewis Structure of Phosphorus dioxide (O2P)
Chemical Formula O2P
CAS Number 12164-00-6
Total Valence Electrons 17
Lewis Structure P–O double bond and P–O single bond
Electron-Domain Geometry trigonal planar
Molecular Geometry bent
Hybridization Model sp2 (central P)
Bond Angle ≈119°
Polarity Polar molecule
PubChem (CID 139273) and NIST list Phosphorus dioxide as O 2P with CAS 12164-00-6; molecular weight ≈ 62.973 g/mol. View CAS 12164-00-6 dictionary details on Guidechem →

Applications of Phosphorus dioxide (CAS 12164-00-6)

The P oxide Phosphorus dioxide is a key industrial intermediate. Nonmetal oxides such as SO3 and P4O10 are acid anhydrides for sulfuric and phosphoric acid manufacture, while metal/semimetal oxides are ceramics, refractories, catalysts and pigment precursors.

Acid Anhydride / Intermediate Gateway to the corresponding oxoacid and its salts (fertilizers, detergents).
Materials & Catalysis Oxide ceramics, refractories, catalysts and pigment feedstocks.
Process Gas / Reagent Oxidizing or reactive reagent in inorganic and environmental processing.
Procurement Note "Phosphorus dioxide" is supplied in multiple commercial grades and package sizes. Specify purity, grade, moisture/impurity limits, package (cylinder, drum or bulk) and intended process, and use CAS 12164-00-6 as the primary identifier when screening suppliers; always confirm regional availability and safety documentation (SDS).

Step 1 - Valence Electrons & Central Atom

To draw the Phosphorus dioxide Lewis structure we first count the total valence electrons. O2P contains 2×6 (O) + 5 (P); the net charge of 0 gives a total of 17 valence electrons to place.

The central atom is P. It is the least electronegative atom capable of forming multiple bonds and is surrounded by the more electronegative terminal atom(s); hydrogen, when present, always occupies a terminal position. Electronegativity considerations place the electron density toward the terminal atom(s).

Valence-electron count

Total valence electrons = 2×6 (O) + 5 (P) = 17 electrons.

Step 2 - Lewis Structure & Electron Distribution

Place P at the center and connect each surrounding atom with a single bond, complete octets on the terminal atoms, and place any remaining electrons on the central atom. The resulting electron distribution is: P–O double bond and P–O single bond; one lone pair on P.

Counting bonding and nonbonding electrons around P therefore satisfies the octet/expanded-octet requirement for the drawn structure.

This species is best represented by resonance structures; the π bonding is delocalized over the equivalent terminal atom(s), so all P–terminals bonds are equivalent in the resonance hybrid.

P=O P–O
P: 1 lone pair, 2 bonding domains
2 bonding domains + 1 lone pairs = 3 electron domains
Octet Rule: Why P Has Eight Electrons P forms 2 bond(s) and retains 2 nonbonding electron(s), reaching an octet. No expanded octet is required for this second-row (or octet-satisfying) central atom.

Step 3 - VSEPR Theory & Geometry

VSEPR theory states that the 3 electron domains around P arrange to minimize mutual repulsion, giving an trigonal planar electron-domain geometry.

Because 1 of these domains are lone pair(s) — and lone pairs repel more strongly than bonding pairs — the observed molecular geometry is bent; the P bond angle is set to ≈119° rather than the ideal value for the electron-domain geometry.

Repulsion hierarchy

A useful VSEPR approximation is: lone pair–lone pair repulsion > lone pair–bonding pair repulsion > bonding pair–bonding pair repulsion. With 1 lone pair(s) on P, the lone-pair domains occupy positions that minimize overall repulsion while pushing the bonding domains (and therefore the bonded atoms) closer together.

Hybridization & Formal Charge

In the conventional localized-bond model, P uses sp2 hybrid orbitals to form the 3 equivalent electron-domain directions (2 bonding + 1 lone pair).

Formal-charge check

Formal charge on central P = V − N − ½B = 5 − 2 − ½×6 = 0. The preferred Lewis structure carries zero formal charge on the central atom (and on the terminals), so it is the dominant contributor.

Modeling Note Modeling Note: sp2 is a compact model for the 3 electron-domain directions around P; full quantum-chemical treatments use molecular orbitals.

Is Phosphorus dioxide Polar or Nonpolar?

Phosphorus dioxide is polar. The bent shape prevents cancellation of the bond dipoles. The bond dipoles do not cancel, leaving a net molecular dipole, which strongly influences solvation behavior and intermolecular interactions.

Expert Quote — Structural Chemistry Perspective

The decisive structural fact is not simply that the individual bonds are polar; it is whether molecular symmetry allows their vector sum to vanish. In Phosphorus dioxide the bent arrangement prevents cancellation, so a permanent dipole remains.

Interpretation consistent with standard VSEPR / molecular-geometry references.

This polarity profile underpins its behavior as a solvent, reactant or process intermediate; when sourcing, specify grade and container compatibility.

Structural Comparison Table

Species Formula Central Atom Electron Domains Molecular Geometry Polarity
Phosphorus dioxide O2P P 3 bent Polar
Phosphine H3P P 4 trigonal pyramidal Polar
Phosphorus trichloride Cl3P P 4 trigonal pyramidal Polar
Phosphorus pentachloride Cl5P P 5 trigonal bipyramidal Nonpolar
Phosphorus trifluoride F3P P 4 trigonal pyramidal Polar
Phosphorus pentafluoride F5P P 5 trigonal bipyramidal Nonpolar
Practice question Starting from the 17 valence electrons of O2P, draw the Lewis structure and confirm the central P atom is sp2-hybridized with bent geometry. What happens to the bond angle if one terminal atom is replaced by a more electronegative substituent?
Looking for industrial bulk or specified-grade supplies of Phosphorus dioxide (CAS 12164-00-6)? Browse Supplier on Guidechem →

FAQs

Is O2P polar or nonpolar?

Phosphorus dioxide is polar. Its bent geometry (and/or unequal terminal atoms) stops the bond dipoles from cancelling.

What is the Lewis structure of Phosphorus dioxide?

P–O double bond and P–O single bond; one lone pair on P. It uses all 17 valence electrons and the preferred structure carries zero formal charge on the central atom.

What is the bond angle in Phosphorus dioxide?

The P angle is about ≈119°. Lone-pair repulsion compresses the angle from the ideal trigonal planar value.

What is the hybridization of P in Phosphorus dioxide?

The conventional model is sp2. Phosphorus dioxide has 3 electron domains around the central P.

What is the CAS number of Phosphorus dioxide?

The CAS number is 12164-00-6. PubChem (CID 139273) and NIST identify this with O2P; use it to locate suppliers and database records.

References

  1. PubChem CID 139273, Phosphorus dioxide. Molecular formula, CAS number, molecular weight and chemical identity.
  2. NIST Chemistry WebBook, SRD 69, Phosphorus dioxide. Formula, CAS Registry Number and thermochemical / spectroscopic data.
  3. IUPAC Gold Book. Definitions for "lone pair", "VSEPR", "hybridization" and "formal charge".
  4. Atkins, P. & de Paula, J., Physical Chemistry. VSEPR, molecular geometry and dipole moments.
  5. Guidechem supplier & dictionary records. Commercial sourcing and CAS-linked property pages for Phosphorus dioxide (CAS 12164-00-6).

Technical scope: Lewis structures, VSEPR and hybridization are model-based descriptions for chemical communication and structure prediction; actual molecular electronic structure is more accurately represented by molecular-orbital and quantum-chemical methods. Commercial grades vary substantially by supplier and intended use; CAS 12164-00-6 identifies the substance, not a universal purity specification.

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