Periodic acid Lewis Structure

Periodic acid Lewis Structure: HIO₄ Lewis Structure, tetrahedral Geometry, sp3 Hybridization & Polarity

Periodic acid Key Facts

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

Figure 1: Lewis Structure of Periodic acid (HIO₄)

Chemical Formula	HIO₄
CAS Number	10450-60-9
Total Valence Electrons	32
Lewis Structure	I–O single bond, I–O double bond, I–O double bond and I–O double bond
Electron-Domain Geometry	tetrahedral
Molecular Geometry	tetrahedral
Hybridization Model	sp3 (central I)
Bond Angle	109.5°
Polarity	Nonpolar molecule

PubChem (CID 65185) and NIST list Periodic acid as HIO ₄ with CAS 10450-60-9; molecular weight ≈ 191.910 g/mol. View CAS 10450-60-9 dictionary details on Guidechem →

Applications of Periodic acid (CAS 10450-60-9)

Periodic acid is encountered as a reagent, intermediate or specialty chemical in inorganic, organometallic and materials synthesis. Confirm grade, purity and supplier documentation (SDS) before specifying for a process.

Reagent / Intermediate Used in synthesis and formulation where the substance's reactivity is required.

Specialty Chemical Specified by grade for the intended process or research use.

Sourcing Verify purity, package and regional availability via the CAS identifier.

Procurement Note "Periodic acid" 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 10450-60-9 as the primary identifier when screening suppliers; always confirm regional availability and safety documentation (SDS).

Step 1 - Valence Electrons & Central Atom

To draw the Periodic acid Lewis structure we first count the total valence electrons. HIO₄ contains 1 (H) + 7 (I) + 4×6 (O); the net charge of 0 gives a total of 32 valence electrons to place.

The central atom is I. 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 = 1 (H) + 7 (I) + 4×6 (O) = 32 electrons.

Step 2 - Lewis Structure & Electron Distribution

Place I 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: I–O single bond, I–O double bond, I–O double bond and I–O double bond; no lone pairs on I.

Counting bonding and nonbonding electrons around I 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 I–terminals bonds are equivalent in the resonance hybrid.

I–O I=O I=O I=O

I: 0 lone pairs, 4 bonding domains

4 bonding domains + 0 lone pairs = 4 electron domains

Octet Rule: Why I Has Eight Electrons I 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 I 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 I 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 I, 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, I uses sp3 hybrid orbitals to form the 4 equivalent electron-domain directions (4 bonding + 0 lone pair).

Formal-charge check

Formal charge on central I = V − N − ½B = 7 − 0 − ½×14 = 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 I; full quantum-chemical treatments use molecular orbitals.

Is Periodic acid Polar or Nonpolar?

Periodic acid is nonpolar. Although individual I–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. Periodic acid 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
Periodic acid	HIO₄	I	4	tetrahedral	Nonpolar
Iodine trifluoride	IF₃	I	5	T-shaped	Polar
Iodine pentafluoride	IF₅	I	6	square pyramidal	Polar
Iodine heptafluoride	IF₇	I	7	pentagonal bipyramidal	Nonpolar
Iodine	I₂	I	4	linear (diatomic)	Nonpolar
Hydrogen iodide	HI	I	4	linear (diatomic)	Polar

Practice question Starting from the 32 valence electrons of HIO₄, draw the Lewis structure and confirm the central I 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 Periodic acid (CAS 10450-60-9)? Browse Supplier on Guidechem →

FAQs

Is HIO₄ polar or nonpolar?

Periodic acid is nonpolar. Its tetrahedral symmetry cancels the bond dipoles exactly.

What is the Lewis structure of Periodic acid?

I–O single bond, I–O double bond, I–O double bond and I–O double bond; no lone pairs on I. It uses all 32 valence electrons and the preferred structure carries zero formal charge on the central atom.

What is the bond angle in Periodic acid?

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

What is the hybridization of I in Periodic acid?

The conventional model is sp3. Periodic acid has 4 electron domains around the central I.

What is the CAS number of Periodic acid?

The CAS number is 10450-60-9. PubChem (CID 65185) and NIST identify this with HIO₄; use it to locate suppliers and database records.

References

PubChem CID 65185, Periodic acid. Molecular formula, CAS number, molecular weight and chemical identity.
NIST Chemistry WebBook, SRD 69, Periodic acid. 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 Periodic acid (CAS 10450-60-9).

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 10450-60-9 identifies the substance, not a universal purity specification.

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Periodic acid Lewis Structure