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Calcium phosphate Lewis Structure

Calcium phosphate Lewis structure (Ca3O8P2). P–O single bond, P–O double bond, P–O single bond and P–O single bond. It shows a tetrahedral shape, sp3 hybridization on P, 109.5° bond angles. Includes a comparison table and FAQs. Edmund3 MIN READSeptember 30, 2026

Calcium phosphate Lewis Structure: Ca3O8P2 Lewis Structure, tetrahedral Geometry, sp3 Hybridization & Polarity

Calcium phosphate Lewis structure Cover

Calcium phosphate Key Facts

The Calcium phosphate Lewis structure is P–O single bond, P–O double bond, P–O single bond and P–O single bond; the central P has 4 electron domains (0 lone pairs), giving a tetrahedral electron-domain arrangement and a tetrahedral molecular geometry with a 109.5° bond angle. P is best described as sp3-hybridized, and Calcium phosphate is nonpolar because the bond dipoles cancel by molecular symmetry.

Calcium phosphate Lewis Structure Figure 1: Lewis Structure of Calcium phosphate (Ca3O8P2)
Chemical Formula Ca3O8P2
CAS Number 7758-87-4
Total Valence Electrons 64
Lewis Structure P–O single bond, P–O double bond, P–O single bond and P–O single bond
Electron-Domain Geometry tetrahedral
Molecular Geometry tetrahedral
Hybridization Model sp3 (central P)
Bond Angle 109.5°
Polarity Nonpolar molecule
PubChem (CID 24456) and NIST list Calcium phosphate as Ca 3O 8P 2 with CAS 7758-87-4; molecular weight ≈ 310.18 g/mol. View CAS 7758-87-4 dictionary details on Guidechem →

Applications of Calcium phosphate (CAS 7758-87-4)

This organic compound is used as a solvent, intermediate or specialty reagent in fine-chemical, pharmaceutical and materials synthesis; specify grade and impurity profile when sourcing.

Solvent / Reagent Medium for reactions, extraction or formulation.
Intermediate Building block for downstream derivatives.
Specialty Use Targeted role in pharma/fragrance/materials.
Procurement Note "Calcium phosphate" 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 7758-87-4 as the primary identifier when screening suppliers; always confirm regional availability and safety documentation (SDS).

Step 1 - Valence Electrons & Central Atom

To draw the Calcium phosphate Lewis structure we first count the total valence electrons. Ca3O8P2 contains 3×2 (Ca) + 8×6 (O) + 2×5 (P); the net charge of 0 gives a total of 64 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 = 3×2 (Ca) + 8×6 (O) + 2×5 (P) = 64 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 single bond, P–O double bond, P–O single bond and P–O single bond; no lone pairs 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–O P–O
P: 0 lone pairs, 4 bonding domains
4 bonding domains + 0 lone pairs = 4 electron domains
Octet Rule: Why P Has Eight Electrons P forms 4 bond(s) and retains 0 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 4 electron domains around P arrange to minimize mutual repulsion, giving an tetrahedral electron-domain geometry.

Because 0 of these domains are lone pair(s) — and lone pairs repel more strongly than bonding pairs — the observed molecular geometry is tetrahedral; the P bond angle is set to 109.5° 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 0 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 sp3 hybrid orbitals to form the 4 equivalent electron-domain directions (4 bonding + 0 lone pair).

Formal-charge check

Formal charge on central P = V − N − ½B = 5 − 0 − ½×10 = 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: sp3 is a compact model for the 4 electron-domain directions around P; full quantum-chemical treatments use molecular orbitals.

Is Calcium phosphate Polar or Nonpolar?

Calcium phosphate is nonpolar. Although individual P–terminal bonds are polar when the atoms differ in electronegativity, the tetrahedral geometry makes their vector sum zero, so there is no net molecular dipole.

Expert Quote — Structural Chemistry Perspective

A common misconception is that polar bonds guarantee a polar molecule. Calcium phosphate shows the opposite: identical bond dipoles arranged with tetrahedral symmetry cancel exactly, yielding a nonpolar species.

Interpretation consistent with standard VSEPR / molecular-geometry references.

Its nonpolar character governs solvation and intermolecular behavior; specify grade and handling when sourcing.

Structural Comparison Table

Species Formula Central Atom Electron Domains Molecular Geometry Polarity
Calcium phosphate Ca3O8P2 P 4 tetrahedral Nonpolar
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 64 valence electrons of Ca3O8P2, draw the Lewis structure and confirm the central P atom is sp3-hybridized with tetrahedral 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 Calcium phosphate (CAS 7758-87-4)? Browse Supplier on Guidechem →

FAQs

Is Ca3O8P2 polar or nonpolar?

Calcium phosphate is nonpolar. Its tetrahedral symmetry cancels the bond dipoles exactly.

What is the Lewis structure of Calcium phosphate?

P–O single bond, P–O double bond, P–O single bond and P–O single bond; no lone pairs on P. It uses all 64 valence electrons and the preferred structure carries zero formal charge on the central atom.

What is the bond angle in Calcium phosphate?

The P angle is about 109.5°. Lone-pair repulsion compresses the angle from the ideal tetrahedral value.

What is the hybridization of P in Calcium phosphate?

The conventional model is sp3. Calcium phosphate has 4 electron domains around the central P.

What is the CAS number of Calcium phosphate?

The CAS number is 7758-87-4. PubChem (CID 24456) and NIST identify this with Ca3O8P2; use it to locate suppliers and database records.

References

  1. PubChem CID 24456, Calcium phosphate. Molecular formula, CAS number, molecular weight and chemical identity.
  2. NIST Chemistry WebBook, SRD 69, Calcium phosphate. 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 Calcium phosphate (CAS 7758-87-4).

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 7758-87-4 identifies the substance, not a universal purity specification.

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