Hydrogen selenide Lewis Structure

Hydrogen selenide Lewis Structure: H₂Se Lewis Structure, bent Geometry, sp3 Hybridization & Polarity

Hydrogen selenide Key Facts

The Hydrogen selenide Lewis structure is 2 Se–H 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 Hydrogen selenide is polar because the bent shape (and/or unequal terminal atoms) prevents cancellation of the bond dipoles.

Figure 1: Lewis Structure of Hydrogen selenide (H₂Se)

Chemical Formula	H₂Se
CAS Number	7783-07-5
Total Valence Electrons	8
Lewis Structure	2 Se–H single bond
Electron-Domain Geometry	tetrahedral
Molecular Geometry	bent
Hybridization Model	sp3 (central Se)
Bond Angle	≈104.5°
Polarity	Polar molecule

PubChem (CID 533) and NIST list Hydrogen selenide as H ₂Se with CAS 7783-07-5; molecular weight ≈ 80.99 g/mol. View CAS 7783-07-5 dictionary details on Guidechem →

Applications of Hydrogen selenide (CAS 7783-07-5)

As a hydride of Se, Hydrogen selenide 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 Se in the preparation of derivatives and doped materials.

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

Procurement Note "Hydrogen selenide" 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 7783-07-5 as the primary identifier when screening suppliers; always confirm regional availability and safety documentation (SDS).

Step 1 - Valence Electrons & Central Atom

To draw the Hydrogen selenide Lewis structure we first count the total valence electrons. H₂Se contains 2×1 (H) + 6 (Se); the net charge of 0 gives a total of 8 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 = 2×1 (H) + 6 (Se) = 8 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: 2 Se–H 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–H ×2

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 = 2. 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 Se; full quantum-chemical treatments use molecular orbitals.

Is Hydrogen selenide Polar or Nonpolar?

Hydrogen selenide 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 Hydrogen selenide 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
Hydrogen selenide	H₂Se	Se	4	bent	Polar
Selenium dioxide	O₂Se	Se	3	bent	Polar

Practice question Starting from the 8 valence electrons of H₂Se, 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 Hydrogen selenide (CAS 7783-07-5)? Browse Supplier on Guidechem →

FAQs

Is H₂Se polar or nonpolar?

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

What is the Lewis structure of Hydrogen selenide?

2 Se–H single bond; 2 lone pairs on Se. It uses all 8 valence electrons and the preferred structure carries a formal charge of 2 on the central atom.

What is the bond angle in Hydrogen selenide?

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 Hydrogen selenide?

The conventional model is sp3. Hydrogen selenide has 4 electron domains around the central Se.

What is the CAS number of Hydrogen selenide?

The CAS number is 7783-07-5. PubChem (CID 533) and NIST identify this with H₂Se; use it to locate suppliers and database records.

References

PubChem CID 533, Hydrogen selenide. Molecular formula, CAS number, molecular weight and chemical identity.
NIST Chemistry WebBook, SRD 69, Hydrogen selenide. 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 Hydrogen selenide (CAS 7783-07-5).

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 7783-07-5 identifies the substance, not a universal purity specification.

Make Guideview Preferred Source on Google

Hydrogen selenide Lewis Structure