Electronegativity-a perspective.

Area of Science:

• Chemistry
• Quantum Chemistry
• Theoretical Chemistry

Background:

• Electronegativity is a fundamental chemical concept representing an atom's electron-attracting power within a molecule.
• Existing electronegativity scales are not derived from direct experimental measurement but are based on empirical observations and theoretical models.
• A density functional theory (DFT)-linked approach defines electronegativity as the negative electronic chemical potential, but faces challenges with non-continuous functions.

Purpose of the Study:

• To critically evaluate the DFT-linked definition of electronegativity.
• To propose and validate an alternative, chemically sound formulation for atomic electronegativity.
• To address the limitations of existing electronegativity models.

Main Methods:

• Analysis of the mathematical and chemical validity of the DFT-based electronegativity definition.
• Development of a new atomic electronegativity formulation based on average local ionization energy.
• Evaluation of the proposed method against chemical principles and experimental observations.

Main Results:

• The DFT-linked electronegativity approach yields chemically invalid predictions due to issues with differentiating non-continuous functions.
• The proposed formulation defines atomic electronegativity as the average local ionization energy on an outer contour of the atom's electronic density.
• This new formulation provides a more effective and chemically consistent measure of electronegativity.

Conclusions:

• The conventional understanding of electronegativity as electron-attractivity is useful but lacks direct experimental basis.
• The DFT-linked electronegativity definition is problematic and can lead to chemically incorrect results.
• A novel formulation based on average local ionization energy offers a robust and chemically valid method for determining atomic electronegativity.