Magnesium hydride Lewis Structure

Magnesium hydride Lewis Structure: H₂Mg Lewis Structure, see text Geometry, sp3 Hybridization & Polarity

Magnesium hydride Key Facts

The Magnesium hydride Lewis structure is central Mg bonded; the central Mg has 0 electron domains (0 lone pairs), giving a tetrahedral electron-domain arrangement and a see text molecular geometry with a — bond angle. Mg is best described as sp3-hybridized, and Magnesium hydride is polar because the see text shape (and/or unequal terminal atoms) prevents cancellation of the bond dipoles.

Figure 1: Lewis Structure of Magnesium hydride (H₂Mg)

Chemical Formula	H₂Mg
CAS Number	7693-27-8
Total Valence Electrons	4
Lewis Structure	central Mg bonded
Electron-Domain Geometry	tetrahedral
Molecular Geometry	see text
Hybridization Model	sp3 (central Mg)
Bond Angle	—
Polarity	Polar molecule

PubChem (CID 5486771) and NIST list Magnesium hydride as H ₂Mg with CAS 7693-27-8; molecular weight ≈ 26.321 g/mol. View CAS 7693-27-8 dictionary details on Guidechem →

Applications of Magnesium hydride (CAS 7693-27-8)

Magnesium 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 "Magnesium 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 7693-27-8 as the primary identifier when screening suppliers; always confirm regional availability and safety documentation (SDS).

Step 1 - Valence Electrons & Central Atom

To draw the Magnesium hydride Lewis structure we first count the total valence electrons. H₂Mg contains 2×1 (H) + 2 (Mg); the net charge of 0 gives a total of 4 valence electrons to place.

The central atom is Mg. 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) + 2 (Mg) = 4 electrons.

Step 2 - Lewis Structure & Electron Distribution

Place Mg 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: central Mg bonded; no lone pairs on Mg.

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

Mg: 0 lone pairs, 0 bonding domains

0 bonding domains + 0 lone pairs = 0 electron domains

Octet Rule: Why Mg Has Eight Electrons Mg forms 0 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 0 electron domains around Mg 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 see text; the Mg bond angle is set to — 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 Mg, 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, Mg uses sp3 hybrid orbitals to form the 0 equivalent electron-domain directions (0 bonding + 0 lone pair).

Formal-charge check

Formal charge on central Mg = V − N − ½B = 2 − 0 − ½×0 = 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 0 electron-domain directions around Mg; full quantum-chemical treatments use molecular orbitals.

Is Magnesium hydride Polar or Nonpolar?

Magnesium hydride is polar. The see text 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 Magnesium hydride the see text 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
Magnesium hydride	H₂Mg	Mg	0	see text	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 4 valence electrons of H₂Mg, draw the Lewis structure and confirm the central Mg atom is sp3-hybridized with see text 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 Magnesium hydride (CAS 7693-27-8)? Browse Supplier on Guidechem →

FAQs

Is H₂Mg polar or nonpolar?

Magnesium hydride is polar. Its see text geometry (and/or unequal terminal atoms) stops the bond dipoles from cancelling.

What is the Lewis structure of Magnesium hydride?

central Mg bonded; no lone pairs on Mg. It uses all 4 valence electrons and the preferred structure carries a formal charge of 2 on the central atom.

What is the bond angle in Magnesium hydride?

The Mg angle is about —. Lone-pair repulsion compresses the angle from the ideal tetrahedral value.

What is the hybridization of Mg in Magnesium hydride?

The conventional model is sp3. Magnesium hydride has 0 electron domains around the central Mg.

What is the CAS number of Magnesium hydride?

The CAS number is 7693-27-8. PubChem (CID 5486771) and NIST identify this with H₂Mg; use it to locate suppliers and database records.

References

PubChem CID 5486771, Magnesium hydride. Molecular formula, CAS number, molecular weight and chemical identity.
NIST Chemistry WebBook, SRD 69, Magnesium 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 Magnesium hydride (CAS 7693-27-8).

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 7693-27-8 identifies the substance, not a universal purity specification.

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Magnesium hydride Lewis Structure