Iodine Lewis Structure

Iodine Lewis Structure: I₂ Lewis Structure, linear (diatomic) Geometry, sp3 Hybridization & Polarity

Iodine Key Facts

The Iodine Lewis structure is a linear diatomic with a nonpolar bond between its two atoms; because the two atoms are identical, Iodine is nonpolar.

Figure 1: Lewis Structure of Iodine (I₂)

Chemical Formula	I₂
CAS Number	7553-56-2
Total Valence Electrons	14
Lewis Structure	linear diatomic molecule with one single bond and a lone pair on each atom
Electron-Domain Geometry	linear
Molecular Geometry	linear (diatomic)
Hybridization Model	sp3
Bond Angle	180°
Polarity	Nonpolar molecule

PubChem (CID 807) and NIST list Iodine as I ₂ with CAS 7553-56-2; molecular weight ≈ 253.8089 g/mol. View CAS 7553-56-2 dictionary details on Guidechem →

Applications of Iodine (CAS 7553-56-2)

Iodine 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 "Iodine" 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 7553-56-2 as the primary identifier when screening suppliers; always confirm regional availability and safety documentation (SDS).

Step 1 - Valence Electrons & Central Atom

To draw the Iodine Lewis structure we first count the total valence electrons. I₂ contains 2×7 (I); the net charge of 0 gives a total of 14 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 = 2×7 (I) = 14 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: linear diatomic molecule with one single bond and a lone pair on each atom.

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

I–X

I: 3 lone pairs, 1 bonding domain

1 bonding domains + 3 lone pairs = 4 electron domains

Octet & Diradical Note In a simple Lewis drawing each atom of this homonuclear diatomic carries lone pairs; species such as O₂ are more accurately described by molecular-orbital theory (paramagnetism arises from unpaired electrons in π* orbitals).

Step 3 - VSEPR Theory & Geometry

VSEPR theory states that the 4 electron domains around I arrange to minimize mutual repulsion, giving an linear 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 linear (diatomic); the I bond angle is set to 180° 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 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 (1 bonding + 3 lone pair).

Formal-charge check

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

Is Iodine Polar or Nonpolar?

Iodine is nonpolar. Although individual I–terminal bonds are polar when the atoms differ in electronegativity, the linear (diatomic) 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. Iodine shows the opposite: identical bond dipoles arranged with linear (diatomic) 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
Iodine	I₂	I	4	linear (diatomic)	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
Hydrogen iodide	HI	I	4	linear (diatomic)	Polar

Practice question Starting from the 14 valence electrons of I₂, draw the Lewis structure and confirm the central I atom is sp3-hybridized with linear (diatomic) 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 Iodine (CAS 7553-56-2)? Browse Supplier on Guidechem →

FAQs

Is I₂ polar or nonpolar?

Iodine is nonpolar. Its linear (diatomic) symmetry cancels the bond dipoles exactly.

What is the Lewis structure of Iodine?

linear diatomic molecule with one single bond and a lone pair on each atom. It uses all 14 valence electrons and the preferred structure carries zero formal charge on the central atom.

What is the bond angle in Iodine?

The I angle is about 180°. Lone-pair repulsion compresses the angle from the ideal linear value.

What is the hybridization of I in Iodine?

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

What is the CAS number of Iodine?

The CAS number is 7553-56-2. PubChem (CID 807) and NIST identify this with I₂; use it to locate suppliers and database records.

References

PubChem CID 807, Iodine. Molecular formula, CAS number, molecular weight and chemical identity.
NIST Chemistry WebBook, SRD 69, Iodine. 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 Iodine (CAS 7553-56-2).

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 7553-56-2 identifies the substance, not a universal purity specification.

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Iodine Lewis Structure

Iodine Lewis Structure