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Selenium oxybromide Lewis Structure

Selenium oxybromide Lewis structure (Br2OSe). Se–O double bond, Se–Br single bond and Se–Br single bond. It shows a trigonal pyramidal shape, sp3 hybridization on Se, ≈107° bond angles. Includes a comparison table and FAQs. Katie3 MIN READSeptember 30, 2026

Selenium oxybromide Lewis Structure: Br2OSe Lewis Structure, trigonal pyramidal Geometry, sp3 Hybridization & Polarity

Selenium oxybromide Lewis structure Cover

Selenium oxybromide Key Facts

The Selenium oxybromide Lewis structure is Se–O double bond, Se–Br single bond and Se–Br single bond; the central Se has 4 electron domains (1 lone pair), giving a tetrahedral electron-domain arrangement and a trigonal pyramidal molecular geometry with a ≈107° bond angle. Se is best described as sp3-hybridized, and Selenium oxybromide is polar because the trigonal pyramidal shape (and/or unequal terminal atoms) prevents cancellation of the bond dipoles.

Selenium oxybromide Lewis Structure Figure 1: Lewis Structure of Selenium oxybromide (Br2OSe)
Chemical Formula Br2OSe
CAS Number 7789-51-7
Total Valence Electrons 26
Lewis Structure Se–O double bond, Se–Br single bond and Se–Br single bond
Electron-Domain Geometry tetrahedral
Molecular Geometry trigonal pyramidal
Hybridization Model sp3 (central Se)
Bond Angle ≈107°
Polarity Polar molecule
PubChem (CID 82242) and NIST list Selenium oxybromide as Br 2OSe with CAS 7789-51-7; molecular weight ≈ 254.78 g/mol. View CAS 7789-51-7 dictionary details on Guidechem →

Applications of Selenium oxybromide (CAS 7789-51-7)

The Se oxide Selenium oxybromide is a key industrial intermediate. Nonmetal oxides such as SO3 and P4O10 are acid anhydrides for sulfuric and phosphoric acid manufacture, while metal/semimetal oxides are ceramics, refractories, catalysts and pigment precursors.

Acid Anhydride / Intermediate Gateway to the corresponding oxoacid and its salts (fertilizers, detergents).
Materials & Catalysis Oxide ceramics, refractories, catalysts and pigment feedstocks.
Process Gas / Reagent Oxidizing or reactive reagent in inorganic and environmental processing.
Procurement Note "Selenium oxybromide" 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 7789-51-7 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 oxybromide Lewis structure we first count the total valence electrons. Br2OSe contains 2×7 (Br) + 6 (O) + 6 (Se); the net charge of 0 gives a total of 26 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 (Br) + 6 (O) + 6 (Se) = 26 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–O double bond, Se–Br single bond and Se–Br single bond; one lone pair on Se.

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

Se=O Se–Br Se–Br
Se: 1 lone pair, 3 bonding domains
3 bonding domains + 1 lone pairs = 4 electron domains
Octet Rule: Why Se Has Eight Electrons Se forms 3 bond(s) and retains 2 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 1 of these domains are lone pair(s) — and lone pairs repel more strongly than bonding pairs — the observed molecular geometry is trigonal pyramidal; the Se bond angle is set to ≈107° 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 1 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 (3 bonding + 1 lone pair).

Formal-charge check

Formal charge on central Se = V − N − ½B = 6 − 2 − ½×8 = 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 oxybromide Polar or Nonpolar?

Selenium oxybromide is polar. The trigonal pyramidal 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 oxybromide the trigonal pyramidal 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 oxybromide Br2OSe Se 4 trigonal pyramidal Polar
Selenium dioxide O2Se Se 3 bent Polar
Hydrogen selenide H2Se Se 4 bent Polar
Practice question Starting from the 26 valence electrons of Br2OSe, draw the Lewis structure and confirm the central Se atom is sp3-hybridized with trigonal pyramidal 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 oxybromide (CAS 7789-51-7)? Browse Supplier on Guidechem →

FAQs

Is Br2OSe polar or nonpolar?

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

What is the Lewis structure of Selenium oxybromide?

Se–O double bond, Se–Br single bond and Se–Br single bond; one lone pair on Se. It uses all 26 valence electrons and the preferred structure carries zero formal charge on the central atom.

What is the bond angle in Selenium oxybromide?

The Se angle is about ≈107°. Lone-pair repulsion compresses the angle from the ideal tetrahedral value.

What is the hybridization of Se in Selenium oxybromide?

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

What is the CAS number of Selenium oxybromide?

The CAS number is 7789-51-7. PubChem (CID 82242) and NIST identify this with Br2OSe; use it to locate suppliers and database records.

References

  1. PubChem CID 82242, Selenium oxybromide. Molecular formula, CAS number, molecular weight and chemical identity.
  2. NIST Chemistry WebBook, SRD 69, Selenium oxybromide. 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 Selenium oxybromide (CAS 7789-51-7).

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 7789-51-7 identifies the substance, not a universal purity specification.

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