Selenium dichloride Lewis Structure

Selenium dichloride Lewis Structure: Cl₂Se Lewis Structure, bent Geometry, sp3 Hybridization & Polarity

Selenium dichloride Key Facts

The Selenium dichloride Lewis structure is Se–Cl single bond and Se–Cl single bond; the central Se has 4 electron domains (2 lone pairs), giving a tetrahedral electron-domain arrangement and a bent molecular geometry with a ≈104.5° bond angle. Se is best described as sp3-hybridized, and Selenium dichloride is polar because the bent shape (and/or unequal terminal atoms) prevents cancellation of the bond dipoles.

Figure 1: Lewis Structure of Selenium dichloride (Cl₂Se)

Chemical Formula	Cl₂Se
CAS Number	14457-70-6
Total Valence Electrons	20
Lewis Structure	Se–Cl single bond and Se–Cl single bond
Electron-Domain Geometry	tetrahedral
Molecular Geometry	bent
Hybridization Model	sp3 (central Se)
Bond Angle	≈104.5°
Polarity	Polar molecule

PubChem (CID 139762) and NIST list Selenium dichloride as Cl ₂Se with CAS 14457-70-6; molecular weight ≈ 149.87 g/mol. View CAS 14457-70-6 dictionary details on Guidechem →

Applications of Selenium dichloride (CAS 14457-70-6)

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 "Selenium dichloride" 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 14457-70-6 as the primary identifier when screening suppliers; always confirm regional availability and safety documentation (SDS).

Step 1 - Valence Electrons & Central Atom

To draw the Selenium dichloride Lewis structure we first count the total valence electrons. Cl₂Se contains 2×7 (Cl) + 6 (Se); the net charge of 0 gives a total of 20 valence electrons to place.

The central atom is Se. 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 (Cl) + 6 (Se) = 20 electrons.

Step 2 - Lewis Structure & Electron Distribution

Place Se 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: Se–Cl single bond and Se–Cl single bond; 2 lone pairs on Se.

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

Se–Cl Se–Cl

Se: 2 lone pairs, 2 bonding domains

2 bonding domains + 2 lone pairs = 4 electron domains

Octet Rule: Why Se Has Eight Electrons Se forms 2 bond(s) and retains 4 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 Se arrange to minimize mutual repulsion, giving an tetrahedral electron-domain geometry.

Because 2 of these domains are lone pair(s) — and lone pairs repel more strongly than bonding pairs — the observed molecular geometry is bent; the Se bond angle is set to ≈104.5° 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 2 lone pair(s) on Se, 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, Se uses sp3 hybrid orbitals to form the 4 equivalent electron-domain directions (2 bonding + 2 lone pair).

Formal-charge check

Formal charge on central Se = V − N − ½B = 6 − 4 − ½×4 = 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 Se; full quantum-chemical treatments use molecular orbitals.

Is Selenium dichloride Polar or Nonpolar?

Selenium dichloride is polar. The bent 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 Selenium dichloride the bent 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
Selenium dichloride	Cl₂Se	Se	4	bent	Polar
Selenium dioxide	O₂Se	Se	3	bent	Polar
Hydrogen selenide	H₂Se	Se	4	bent	Polar

Practice question Starting from the 20 valence electrons of Cl₂Se, draw the Lewis structure and confirm the central Se atom is sp3-hybridized with bent 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 Selenium dichloride (CAS 14457-70-6)? Browse Supplier on Guidechem →

FAQs

Is Cl₂Se polar or nonpolar?

Selenium dichloride is polar. Its bent geometry (and/or unequal terminal atoms) stops the bond dipoles from cancelling.

What is the Lewis structure of Selenium dichloride?

Se–Cl single bond and Se–Cl single bond; 2 lone pairs on Se. It uses all 20 valence electrons and the preferred structure carries zero formal charge on the central atom.

What is the bond angle in Selenium dichloride?

The Se angle is about ≈104.5°. Lone-pair repulsion compresses the angle from the ideal tetrahedral value.

What is the hybridization of Se in Selenium dichloride?

The conventional model is sp3. Selenium dichloride has 4 electron domains around the central Se.

What is the CAS number of Selenium dichloride?

The CAS number is 14457-70-6. PubChem (CID 139762) and NIST identify this with Cl₂Se; use it to locate suppliers and database records.

References

PubChem CID 139762, Selenium dichloride. Molecular formula, CAS number, molecular weight and chemical identity.
NIST Chemistry WebBook, SRD 69, Selenium dichloride. 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 Selenium dichloride (CAS 14457-70-6).

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 14457-70-6 identifies the substance, not a universal purity specification.

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Selenium dichloride Lewis Structure

Selenium dichloride Lewis Structure