Electronegativity and Bond Type Calculator

Electronegativity Electronegativity (EN) measures an atom’s tendency to attract shared electrons in a bond. Proposed by Linus Pauling (USA, 1932) — Nobel Prize in Chemistry 1954. Pauling scale: dimensionless, ranges from ~0.7 (Cs) to 4.0 (F). Fluorine is the most electronegative element (4.0). Cesium is the least (0.7).

Bond Type from ΔEN Pauling’s rules (ΔEN = |EN₁ − EN₂|): ΔEN < 0.5: Nonpolar covalent — electrons shared nearly equally (H₂, CH₄) 0.5 ≤ ΔEN < 1.7: Polar covalent, unequal sharing; dipole moment (HCl, H₂O) ΔEN ≥ 1.7: Ionic — electron fully transferred; forms ions (NaCl, MgO) Note: these boundaries are approximate — ionic character is a continuous spectrum.

Percent Ionic Character Hanney-Smith formula: % ionic = 16(ΔEN) + 3.5(ΔEN)² At ΔEN = 1.7, ~50% ionic character — often used as the ionic/covalent boundary. At ΔEN = 3.3 (e.g., CsF), ~92% ionic character.

Dipole Moment Polar covalent bonds create a dipole moment: μ = δ × d Where δ = partial charge, d = bond length. A molecule with polar bonds may still be nonpolar overall if geometry is symmetric (CO₂, CCl₄).

Periodic Trends Electronegativity increases across a period (left to right). Electronegativity decreases down a group (top to bottom). Exception: noble gases are not assigned EN values (they rarely form bonds). Metals: low EN (0.7–1.8). Nonmetals: high EN (2.0–4.0). Metalloids: intermediate.