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Periodate ion Lewis Structure

Periodate ion Lewis structure (IO4-), net charge -1. I–O single bond, I–O double bond, I–O double bond and I–O double bond. It shows a tetrahedral shape, sp3 hybridization on I, 109.5° bond angles. Includes a comparison table and FAQs. Waite3 MIN READSeptember 30, 2026

Periodate ion Lewis Structure: IO4- Lewis Structure, tetrahedral Geometry, sp3 Hybridization & Polarity

Periodate ion Lewis structure Cover

Periodate ion Key Facts

The Periodate ion 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 Periodate ion is nonpolar because the bond dipoles cancel by molecular symmetry.

Periodate ion Lewis Structure Figure 1: Lewis Structure of Periodate ion (IO4-)
Chemical Formula IO4-
CAS Number 15056-35-6
Net Charge -1
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 167232) and NIST list Periodate ion as IO 4- with CAS 15056-35-6; molecular weight ≈ 190.902 g/mol. View CAS 15056-35-6 dictionary details on Guidechem →

Applications of Periodate ion (CAS 15056-35-6)

In aqueous and process chemistry, IO4- exists as the anion Periodate ion ion. It is encountered as a counterion and a controlled source of I in salts, buffers, electrochemistry and analytical protocols, and as a reactant in syntheses that require a defined equivalent of I-containing material.

Ion Source / Counterion Supplied as salts and solutions; specify hydration, counter-cation and concentration.
Analytical & Electrochemical Used in titrations, plating baths and ionic-strength control where the ion is the active species.
Synthesis Reagent A controlled source of I in precipitation, complexation and redox procedures.
Procurement Note "Periodate ion" 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 15056-35-6 as the primary identifier when screening suppliers; always confirm regional availability and safety documentation (SDS).

Step 1 - Valence Electrons & Central Atom

To draw the Periodate ion Lewis structure we first count the total valence electrons. IO4- contains 7 (I) + 4×6 (O) − 1 (net anion); the net charge of -1 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 = 7 (I) + 4×6 (O) − 1 (net anion) = 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 Periodate ion Polar or Nonpolar?

Periodate ion 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. Periodate ion 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
Periodate ion IO4- 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 IO4-, 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 Periodate ion (CAS 15056-35-6)? Browse Supplier on Guidechem →

FAQs

Is IO4- polar or nonpolar?

Periodate ion is nonpolar. Its tetrahedral symmetry cancels the bond dipoles exactly.

What is the Lewis structure of Periodate ion?

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 Periodate ion?

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 Periodate ion?

The conventional model is sp3. Periodate ion has 4 electron domains around the central I.

What is the CAS number of Periodate ion?

The CAS number is 15056-35-6. PubChem (CID 167232) and NIST identify this with IO4-; use it to locate suppliers and database records.

References

  1. PubChem CID 167232, Periodate ion. Molecular formula, CAS number, molecular weight and chemical identity.
  2. NIST Chemistry WebBook, SRD 69, Periodate ion. 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 Periodate ion (CAS 15056-35-6).

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 15056-35-6 identifies the substance, not a universal purity specification.

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