Potassium fluoride Lewis Structure

Potassium fluoride Lewis Structure: FK Lewis Structure, linear (diatomic) Geometry, sp3d Hybridization & Polarity

Potassium fluoride Key Facts

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

Figure 1: Lewis Structure of Potassium fluoride (FK)

Chemical Formula	FK
CAS Number	7789-23-3
Total Valence Electrons	8
Lewis Structure	linear diatomic molecule with one single bond
Electron-Domain Geometry	linear
Molecular Geometry	linear (diatomic)
Hybridization Model	sp3d
Bond Angle	180°
Polarity	Polar molecule

PubChem (CID 522689) and NIST list Potassium fluoride as FK with CAS 7789-23-3; molecular weight ≈ 58.0967 g/mol. View CAS 7789-23-3 dictionary details on Guidechem →

Applications of Potassium fluoride (CAS 7789-23-3)

Potassium fluoride 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 "Potassium fluoride" 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 7789-23-3 as the primary identifier when screening suppliers; always confirm regional availability and safety documentation (SDS).

Step 1 - Valence Electrons & Central Atom

To draw the Potassium fluoride Lewis structure we first count the total valence electrons. FK contains 7 (F) + 1 (K); the net charge of 0 gives a total of 8 valence electrons to place.

The central atom is F. 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 (F) + 1 (K) = 8 electrons.

Step 2 - Lewis Structure & Electron Distribution

Place F 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; 3 lone pair(s) on F.

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

F–K

F: 3 lone pairs, 1 bonding domain

1 bonding domains + 3 lone pairs = 5 electron domains

Expanded Octet: d-Orbital Participation Central F belongs to period 3 or below, so it can accommodate more than eight electrons: low-lying d orbitals become available and the linear (diatomic) arrangement with 5 domains reflects this expanded valence shell. The octet rule alone does not apply to such hypervalent species.

Step 3 - VSEPR Theory & Geometry

VSEPR theory states that the 5 electron domains around F arrange to minimize mutual repulsion, giving an linear electron-domain geometry.

Because 3 of these domains are lone pair(s) — and lone pairs repel more strongly than bonding pairs — the observed molecular geometry is linear (diatomic); the F 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 3 lone pair(s) on F, 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, F uses sp3d hybrid orbitals to form the 5 equivalent electron-domain directions (1 bonding + 3 lone pair).

Formal-charge check

Formal charge on central F = V − N − ½B = 7 − 6 − 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: sp3d / sp3d hybridization is a convenient localized-bond teaching model. Modern quantum-chemical descriptions of hypervalent Potassium fluoride use molecular orbitals and do not require populated d orbitals as the primary bonding picture.

Is Potassium fluoride Polar or Nonpolar?

Potassium fluoride 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 Potassium fluoride 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
Potassium fluoride	FK	F	5	linear (diatomic)	Polar
Hydrogen fluoride	HF	F	4	linear (diatomic)	Polar
Fluorine	F₂	F	4	linear (diatomic)	Nonpolar

Practice question Starting from the 8 valence electrons of FK, draw the Lewis structure and confirm the central F atom is sp3d-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 Potassium fluoride (CAS 7789-23-3)? Browse Supplier on Guidechem →

FAQs

Is FK polar or nonpolar?

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

What is the Lewis structure of Potassium fluoride?

linear diatomic molecule with one single bond; 3 lone pair(s) on F. It uses all 8 valence electrons and the preferred structure carries zero formal charge on the central atom.

What is the bond angle in Potassium fluoride?

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

What is the hybridization of F in Potassium fluoride?

The conventional model is sp3d. Potassium fluoride has 5 electron domains around the central F.

What is the CAS number of Potassium fluoride?

The CAS number is 7789-23-3. PubChem (CID 522689) and NIST identify this with FK; use it to locate suppliers and database records.

References

PubChem CID 522689, Potassium fluoride. Molecular formula, CAS number, molecular weight and chemical identity.
NIST Chemistry WebBook, SRD 69, Potassium fluoride. 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 Potassium fluoride (CAS 7789-23-3).

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 7789-23-3 identifies the substance, not a universal purity specification.

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Potassium fluoride Lewis Structure