Sulfur dibromide Lewis Structure

Sulfur dibromide Lewis Structure: Br₂S Lewis Structure, bent Geometry, sp3 Hybridization & Polarity

Sulfur dibromide Key Facts

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

Figure 1: Lewis Structure of Sulfur dibromide (Br₂S)

Chemical Formula	Br₂S
CAS Number	13965-42-9
Total Valence Electrons	20
Lewis Structure	S–Br single bond and S–Br single bond
Electron-Domain Geometry	tetrahedral
Molecular Geometry	bent
Hybridization Model	sp3 (central S)
Bond Angle	≈104.5°
Polarity	Polar molecule

PubChem (CID 139733) and NIST list Sulfur dibromide as Br ₂S with CAS 13965-42-9; molecular weight ≈ 191.88 g/mol. View CAS 13965-42-9 dictionary details on Guidechem →

Applications of Sulfur dibromide (CAS 13965-42-9)

Sulfur dibromide 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 "Sulfur dibromide" 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 13965-42-9 as the primary identifier when screening suppliers; always confirm regional availability and safety documentation (SDS).

Step 1 - Valence Electrons & Central Atom

To draw the Sulfur dibromide Lewis structure we first count the total valence electrons. Br₂S contains 2×7 (Br) + 6 (S); the net charge of 0 gives a total of 20 valence electrons to place.

The central atom is S. 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 (Br) + 6 (S) = 20 electrons.

Step 2 - Lewis Structure & Electron Distribution

Place S 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: S–Br single bond and S–Br single bond; 2 lone pairs on S.

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

S–Br S–Br

S: 2 lone pairs, 2 bonding domains

2 bonding domains + 2 lone pairs = 4 electron domains

Octet Rule: Why S Has Eight Electrons S 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 S 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 S 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 S, 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, S uses sp3 hybrid orbitals to form the 4 equivalent electron-domain directions (2 bonding + 2 lone pair).

Formal-charge check

Formal charge on central S = 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 S; full quantum-chemical treatments use molecular orbitals.

Is Sulfur dibromide Polar or Nonpolar?

Sulfur dibromide 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 Sulfur dibromide 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
Sulfur dibromide	Br₂S	S	4	bent	Polar
Sulfur dioxide	SO₂	S	3	bent	Polar
Sulfur trioxide	O₃S	S	3	trigonal planar	Nonpolar
Sulfur hexafluoride	F₆S	S	6	octahedral	Nonpolar
Sulfur tetrafluoride	F₄S	S	5	seesaw	Polar
Sulfate	O₄S	S	4	tetrahedral	Nonpolar

Practice question Starting from the 20 valence electrons of Br₂S, draw the Lewis structure and confirm the central S 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 Sulfur dibromide (CAS 13965-42-9)? Browse Supplier on Guidechem →

FAQs

Is Br₂S polar or nonpolar?

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

What is the Lewis structure of Sulfur dibromide?

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

What is the bond angle in Sulfur dibromide?

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

What is the hybridization of S in Sulfur dibromide?

The conventional model is sp3. Sulfur dibromide has 4 electron domains around the central S.

What is the CAS number of Sulfur dibromide?

The CAS number is 13965-42-9. PubChem (CID 139733) and NIST identify this with Br₂S; use it to locate suppliers and database records.

References

PubChem CID 139733, Sulfur dibromide. Molecular formula, CAS number, molecular weight and chemical identity.
NIST Chemistry WebBook, SRD 69, Sulfur dibromide. 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 Sulfur dibromide (CAS 13965-42-9).

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 13965-42-9 identifies the substance, not a universal purity specification.

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Sulfur dibromide Lewis Structure

Sulfur dibromide Lewis Structure