Ammonium bromide Lewis Structure

Ammonium bromide Lewis Structure: BrH₄N Lewis Structure, tetrahedral Geometry, sp3 Hybridization & Polarity

Ammonium bromide Key Facts

The Ammonium bromide Lewis structure is 4 N–H single bond; the central N has 4 electron domains (0 lone pairs), giving a tetrahedral electron-domain arrangement and a tetrahedral molecular geometry with a 109.5° bond angle. N is best described as sp3-hybridized, and Ammonium bromide is nonpolar because the bond dipoles cancel by molecular symmetry.

Figure 1: Lewis Structure of Ammonium bromide (BrH₄N)

Chemical Formula	BrH₄N
CAS Number	12124-97-9
Total Valence Electrons	16
Lewis Structure	4 N–H single bond
Electron-Domain Geometry	tetrahedral
Molecular Geometry	tetrahedral
Hybridization Model	sp3 (central N)
Bond Angle	109.5°
Polarity	Nonpolar molecule

PubChem (CID 25514) and NIST list Ammonium bromide as BrH ₄N with CAS 12124-97-9; molecular weight ≈ 97.94 g/mol. View CAS 12124-97-9 dictionary details on Guidechem →

Applications of Ammonium bromide (CAS 12124-97-9)

As a hydride of N, Ammonium bromide is typically a strong reducing agent, a potential fuel component, or a precursor in inorganic and organometallic synthesis. Many pnictogen/sulfur hydrides are toxic, foul-smelling and pyrophoric or flammable, and are handled with appropriate ventilation and inert-atmosphere technique.

Reducing Agent Electron-rich hydrides reduce metal centers and functional groups in synthesis.

Precursor / Feedstock Source of N in the preparation of derivatives and doped materials.

Handling Often toxic/flammable/pyrophoric; inert atmosphere and active ventilation required.

Procurement Note "Ammonium bromide" 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 12124-97-9 as the primary identifier when screening suppliers; always confirm regional availability and safety documentation (SDS).

Step 1 - Valence Electrons & Central Atom

To draw the Ammonium bromide Lewis structure we first count the total valence electrons. BrH₄N contains 7 (Br) + 4×1 (H) + 5 (N); the net charge of 0 gives a total of 16 valence electrons to place.

The central atom is N. 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 = 7 (Br) + 4×1 (H) + 5 (N) = 16 electrons.

Step 2 - Lewis Structure & Electron Distribution

Place N 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: 4 N–H single bond; no lone pairs on N.

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

N–H ×4

N: 0 lone pairs, 4 bonding domains

4 bonding domains + 0 lone pairs = 4 electron domains

Octet Rule: Why N Has Eight Electrons N forms 4 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 4 electron domains around N arrange to minimize mutual repulsion, giving an tetrahedral 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 tetrahedral; the N bond angle is set to 109.5° 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 0 lone pair(s) on N, 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, N uses sp3 hybrid orbitals to form the 4 equivalent electron-domain directions (4 bonding + 0 lone pair).

Formal-charge check

Formal charge on central N = V − N − ½B = 5 − 0 − ½×8 = 5. The nonzero formal charge is distributed by resonance / charge separation; the drawn structure is the lowest-energy contributor.

Modeling Note Modeling Note: sp3 is a compact model for the 4 electron-domain directions around N; full quantum-chemical treatments use molecular orbitals.

Is Ammonium bromide Polar or Nonpolar?

Ammonium bromide is nonpolar. Although individual N–terminal bonds are polar when the atoms differ in electronegativity, the tetrahedral 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. Ammonium bromide shows the opposite: identical bond dipoles arranged with tetrahedral 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
Ammonium bromide	BrH₄N	N	4	tetrahedral	Nonpolar
Ammonia	H₃N	N	4	trigonal pyramidal	Polar
Ammonium	H₄N	N	4	tetrahedral	Nonpolar
Hydrazine	H₄N₂	N	4	trigonal pyramidal	Polar
Nitrogen	N₂	N	2	linear (diatomic)	Nonpolar
Nitric oxide	NO	N	3	linear (diatomic)	Polar

Practice question Starting from the 16 valence electrons of BrH₄N, draw the Lewis structure and confirm the central N atom is sp3-hybridized with tetrahedral 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 Ammonium bromide (CAS 12124-97-9)? Browse Supplier on Guidechem →

FAQs

Is BrH₄N polar or nonpolar?

Ammonium bromide is nonpolar. Its tetrahedral symmetry cancels the bond dipoles exactly.

What is the Lewis structure of Ammonium bromide?

4 N–H single bond; no lone pairs on N. It uses all 16 valence electrons and the preferred structure carries a formal charge of 5 on the central atom.

What is the bond angle in Ammonium bromide?

The N angle is about 109.5°. Lone-pair repulsion compresses the angle from the ideal tetrahedral value.

What is the hybridization of N in Ammonium bromide?

The conventional model is sp3. Ammonium bromide has 4 electron domains around the central N.

What is the CAS number of Ammonium bromide?

The CAS number is 12124-97-9. PubChem (CID 25514) and NIST identify this with BrH₄N; use it to locate suppliers and database records.

References

PubChem CID 25514, Ammonium bromide. Molecular formula, CAS number, molecular weight and chemical identity.
NIST Chemistry WebBook, SRD 69, Ammonium bromide. 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 Ammonium bromide (CAS 12124-97-9).

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 12124-97-9 identifies the substance, not a universal purity specification.

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Ammonium bromide Lewis Structure