Dibromoacetylene Lewis Structure

Dibromoacetylene Lewis Structure: C₂Br₂ Lewis Structure, linear Geometry, sp Hybridization & Polarity

Dibromoacetylene Key Facts

The Dibromoacetylene Lewis structure is C–C triple bond and C–Br single bond; the central C has 2 electron domains (0 lone pairs), giving a linear electron-domain arrangement and a linear molecular geometry with a 180° bond angle. C is best described as sp-hybridized, and Dibromoacetylene is polar because the linear shape (and/or unequal terminal atoms) prevents cancellation of the bond dipoles.

Figure 1: Lewis Structure of Dibromoacetylene (C₂Br₂)

Chemical Formula	C₂Br₂
CAS Number	4315-21-5
Total Valence Electrons	22
Lewis Structure	C–C triple bond and C–Br single bond
Electron-Domain Geometry	linear
Molecular Geometry	linear
Hybridization Model	sp (central C)
Bond Angle	180°
Polarity	Polar molecule

PubChem (CID 61169) and NIST list Dibromoacetylene as C ₂Br ₂ with CAS 4315-21-5; molecular weight ≈ 183.83 g/mol. View CAS 4315-21-5 dictionary details on Guidechem →

Applications of Dibromoacetylene (CAS 4315-21-5)

Alkenes are polymerization monomers and intermediates: ethylene → polyethylene, propylene → polypropylene, styrene → polystyrene and ABS, butadiene → synthetic rubber. They are also feedstocks for alcohols, oxides and plasticizers.

Polymer Monomer Basis of polyethylene, polypropylene, polystyrene and elastomers.

Intermediate Source of alcohols, epoxides, plasticizers and surfactants.

Process Scale Produced in the largest volumes of any organic commodity class.

Procurement Note "Dibromoacetylene" 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 4315-21-5 as the primary identifier when screening suppliers; always confirm regional availability and safety documentation (SDS).

Step 1 - Valence Electrons & Central Atom

To draw the Dibromoacetylene Lewis structure we first count the total valence electrons. C₂Br₂ contains 2×4 (C) + 2×7 (Br); the net charge of 0 gives a total of 22 valence electrons to place.

The central atom is C. 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 = 2×4 (C) + 2×7 (Br) = 22 electrons.

Step 2 - Lewis Structure & Electron Distribution

Place C 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: C–C triple bond and C–Br single bond; no lone pairs on C.

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

C≡C C–Br

C: 0 lone pairs, 2 bonding domains

2 bonding domains + 0 lone pairs = 2 electron domains

Octet Rule: Why C Has Eight Electrons C forms 2 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 2 electron domains around C arrange to minimize mutual repulsion, giving an linear 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 linear; the C 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 0 lone pair(s) on C, 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, C uses sp hybrid orbitals to form the 2 equivalent electron-domain directions (2 bonding + 0 lone pair).

Formal-charge check

Formal charge on central C = V − N − ½B = 4 − 0 − 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: sp is a compact model for the 2 electron-domain directions around C; full quantum-chemical treatments use molecular orbitals.

Is Dibromoacetylene Polar or Nonpolar?

Dibromoacetylene is polar. The linear 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 Dibromoacetylene the linear 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
Dibromoacetylene	C₂Br₂	C	2	linear	Polar
Carbon dioxide	CO₂	C	2	linear	Nonpolar
Carbon monoxide	CO	C	2	linear (diatomic)	Polar
Carbon disulfide	CS₂	C	2	linear	Nonpolar
Methane	CH₄	C	4	tetrahedral	Nonpolar
Ethane	C₂H₆	C	4	tetrahedral	Nonpolar

Practice question Starting from the 22 valence electrons of C₂Br₂, draw the Lewis structure and confirm the central C atom is sp-hybridized with linear 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 Dibromoacetylene (CAS 4315-21-5)? Browse Supplier on Guidechem →

FAQs

Is C₂Br₂ polar or nonpolar?

Dibromoacetylene is polar. Its linear geometry (and/or unequal terminal atoms) stops the bond dipoles from cancelling.

What is the Lewis structure of Dibromoacetylene?

C–C triple bond and C–Br single bond; no lone pairs on C. It uses all 22 valence electrons and the preferred structure carries zero formal charge on the central atom.

What is the bond angle in Dibromoacetylene?

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

What is the hybridization of C in Dibromoacetylene?

The conventional model is sp. Dibromoacetylene has 2 electron domains around the central C.

What is the CAS number of Dibromoacetylene?

The CAS number is 4315-21-5. PubChem (CID 61169) and NIST identify this with C₂Br₂; use it to locate suppliers and database records.

References

PubChem CID 61169, Dibromoacetylene. Molecular formula, CAS number, molecular weight and chemical identity.
NIST Chemistry WebBook, SRD 69, Dibromoacetylene. 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 Dibromoacetylene (CAS 4315-21-5).

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 4315-21-5 identifies the substance, not a universal purity specification.

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Dibromoacetylene Lewis Structure

Dibromoacetylene Lewis Structure