calcium hydroxide Lewis Structure

calcium hydroxide Lewis Structure: CaH₂O₂ Lewis Structure, see text Geometry, sp3 Hybridization & Polarity

calcium hydroxide Key Facts

The calcium hydroxide Lewis structure is O–H single bond; the central O has 4 electron domains (3 lone pairs), giving a tetrahedral electron-domain arrangement and a see text molecular geometry with a — bond angle. O is best described as sp3-hybridized, and calcium hydroxide is polar because the see text shape (and/or unequal terminal atoms) prevents cancellation of the bond dipoles.

Figure 1: Lewis Structure of calcium hydroxide (CaH₂O₂)

Chemical Formula	CaH₂O₂
CAS Number	1305-62-0
Total Valence Electrons	16
Lewis Structure	O–H single bond
Electron-Domain Geometry	tetrahedral
Molecular Geometry	see text
Hybridization Model	sp3 (central O)
Bond Angle	—
Polarity	Polar molecule

PubChem (CID 6093208) and NIST list calcium hydroxide as CaH ₂O ₂ with CAS 1305-62-0; molecular weight ≈ 74.09 g/mol. View CAS 1305-62-0 dictionary details on Guidechem →

Applications of calcium hydroxide (CAS 1305-62-0)

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 hydroxide" 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 1305-62-0 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 hydroxide Lewis structure we first count the total valence electrons. CaH₂O₂ contains 2 (Ca) + 2×1 (H) + 2×6 (O); the net charge of 0 gives a total of 16 valence electrons to place.

The central atom is O. 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 (Ca) + 2×1 (H) + 2×6 (O) = 16 electrons.

Step 2 - Lewis Structure & Electron Distribution

Place O 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: O–H single bond; 3 lone pairs on O.

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

O–H

O: 3 lone pairs, 1 bonding domain

1 bonding domains + 3 lone pairs = 4 electron domains

Octet Rule: Why O Has Eight Electrons O forms 1 bond(s) and retains 6 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 O arrange to minimize mutual repulsion, giving an tetrahedral electron-domain geometry.

Because 3 of these domains are lone pair(s) — and lone pairs repel more strongly than bonding pairs — the observed molecular geometry is see text; the O bond angle is set to — 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 3 lone pair(s) on O, 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, O uses sp3 hybrid orbitals to form the 4 equivalent electron-domain directions (1 bonding + 3 lone pair).

Formal-charge check

Formal charge on central O = V − N − ½B = 6 − 6 − ½×2 = 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 O; full quantum-chemical treatments use molecular orbitals.

Is calcium hydroxide Polar or Nonpolar?

calcium hydroxide is polar. The see text 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 calcium hydroxide the see text 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
calcium hydroxide	CaH₂O₂	O	4	see text	Polar
Water	H₂O	O	4	bent	Polar
Hydrogen peroxide	H₂O₂	O	4	bent	Polar
Ozone	O₃	O	3	bent	Polar
Hydronium	H₃O	O	4	trigonal pyramidal	Polar
Hypochlorite	ClO	O	4	linear (diatomic)	Polar

Practice question Starting from the 16 valence electrons of CaH₂O₂, draw the Lewis structure and confirm the central O atom is sp3-hybridized with see text 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 hydroxide (CAS 1305-62-0)? Browse Supplier on Guidechem →

FAQs

Is CaH₂O₂ polar or nonpolar?

calcium hydroxide is polar. Its see text geometry (and/or unequal terminal atoms) stops the bond dipoles from cancelling.

What is the Lewis structure of calcium hydroxide?

O–H single bond; 3 lone pairs on O. It uses all 16 valence electrons and the preferred structure carries zero formal charge on the central atom.

What is the bond angle in calcium hydroxide?

The O angle is about —. Lone-pair repulsion compresses the angle from the ideal tetrahedral value.

What is the hybridization of O in calcium hydroxide?

The conventional model is sp3. calcium hydroxide has 4 electron domains around the central O.

What is the CAS number of calcium hydroxide?

The CAS number is 1305-62-0. PubChem (CID 6093208) and NIST identify this with CaH₂O₂; use it to locate suppliers and database records.

References

PubChem CID 6093208, calcium hydroxide. Molecular formula, CAS number, molecular weight and chemical identity.
NIST Chemistry WebBook, SRD 69, calcium hydroxide. Formula, CAS Registry Number and thermochemical / spectroscopic data.
IUPAC Gold Book. Definitions for "lone pair", "VSEPR", "hybridization" and "formal charge".
Atkins, P. & de Paula, J., Physical Chemistry. VSEPR, molecular geometry and dipole moments.
Guidechem supplier & dictionary records. Commercial sourcing and CAS-linked property pages for calcium hydroxide (CAS 1305-62-0).

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 1305-62-0 identifies the substance, not a universal purity specification.

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calcium hydroxide Lewis Structure