Sodium hydride Lewis Structure

Sodium hydride Lewis Structure: HNa Lewis Structure, linear (diatomic) Geometry, sp Hybridization & Polarity

Sodium hydride Key Facts

The Sodium hydride Lewis structure is a linear diatomic with a polar bond between its two atoms; because the two atoms differ in electronegativity, Sodium hydride is polar.

Figure 1: Lewis Structure of Sodium hydride (HNa)

Chemical Formula	HNa
CAS Number	7646-69-7
Total Valence Electrons	2
Lewis Structure	linear diatomic molecule with one single bond
Electron-Domain Geometry	linear
Molecular Geometry	linear (diatomic)
Hybridization Model	sp
Bond Angle	180°
Polarity	Polar molecule

PubChem (CID 24758) and NIST list Sodium hydride as HNa with CAS 7646-69-7; molecular weight ≈ 23.9977 g/mol. View CAS 7646-69-7 dictionary details on Guidechem →

Applications of Sodium hydride (CAS 7646-69-7)

Sodium hydride 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 "Sodium hydride" 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 7646-69-7 as the primary identifier when screening suppliers; always confirm regional availability and safety documentation (SDS).

Step 1 - Valence Electrons & Central Atom

To draw the Sodium hydride Lewis structure we first count the total valence electrons. HNa contains 1 (H) + 1 (Na); the net charge of 0 gives a total of 2 valence electrons to place.

The central atom is Na. 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 = 1 (H) + 1 (Na) = 2 electrons.

Step 2 - Lewis Structure & Electron Distribution

Place Na 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: linear diatomic molecule with one single bond.

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

Na–H

Na: 0 lone pairs, 1 bonding domain

1 bonding domains + 0 lone pairs = 2 electron domains

Octet & Diradical Note In a simple Lewis drawing each atom of this homonuclear diatomic carries lone pairs; species such as O₂ are more accurately described by molecular-orbital theory (paramagnetism arises from unpaired electrons in π* orbitals).

Step 3 - VSEPR Theory & Geometry

VSEPR theory states that the 2 electron domains around Na 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 (diatomic); the Na 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 Na, 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, Na uses sp hybrid orbitals to form the 2 equivalent electron-domain directions (1 bonding + 0 lone pair).

Formal-charge check

Formal charge on central Na = V − N − ½B = 1 − 0 − ½×2 = 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 Na; full quantum-chemical treatments use molecular orbitals.

Is Sodium hydride Polar or Nonpolar?

Sodium hydride is polar. The linear (diatomic) 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 Sodium hydride the linear (diatomic) 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
Sodium hydride	HNa	Na	2	linear (diatomic)	Polar
Carbon dioxide	CO₂	C	2	linear	Nonpolar
Carbon monoxide	CO	C	2	linear (diatomic)	Polar
Carbon disulfide	CS₂	C	2	linear	Nonpolar

Practice question Starting from the 2 valence electrons of HNa, draw the Lewis structure and confirm the central Na atom is sp-hybridized with linear (diatomic) 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 Sodium hydride (CAS 7646-69-7)? Browse Supplier on Guidechem →

FAQs

Is HNa polar or nonpolar?

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

What is the Lewis structure of Sodium hydride?

linear diatomic molecule with one single bond. It uses all 2 valence electrons and the preferred structure carries zero formal charge on the central atom.

What is the bond angle in Sodium hydride?

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

What is the hybridization of Na in Sodium hydride?

The conventional model is sp. Sodium hydride has 2 electron domains around the central Na.

What is the CAS number of Sodium hydride?

The CAS number is 7646-69-7. PubChem (CID 24758) and NIST identify this with HNa; use it to locate suppliers and database records.

References

PubChem CID 24758, Sodium hydride. Molecular formula, CAS number, molecular weight and chemical identity.
NIST Chemistry WebBook, SRD 69, Sodium hydride. 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 Sodium hydride (CAS 7646-69-7).

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 7646-69-7 identifies the substance, not a universal purity specification.

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Sodium hydride Lewis Structure