About This Electronegativity Calculator
This calculator is designed for fast, classroom‑friendly exploration of electronegativity and bond polarity. You can
select from multiple scales (Pauling, Allen, Mulliken, Allred‑Rochow) and compare two elements at a glance.
The Bond Analyzer panel reports each element’s electronegativity (χ), the absolute difference
Δχ = |χ(A) − χ(B)|, a qualitative bond classification, and an estimated percent ionic character.
The interactive heatmap highlights periodic trends—generally increasing across a period (left to right) and
decreasing down a group—while the ranked table lets you filter and sort values for quick reference.
How the classification works
Bond type is inferred from the magnitude of Δχ using common textbook thresholds. By default this tool uses 0.4 and 1.7,
which means Δχ < 0.4 is treated as nonpolar covalent, 0.4 ≤ Δχ < 1.7 as polar covalent,
and Δχ ≥ 1.7 as ionic. These are adjustable because different courses and references place the boundaries
slightly differently and real bonds exist on a continuum rather than in discrete boxes. For example, H–F with
Δχ ≈ 1.78 is often discussed as a very polar covalent bond despite being near (or just beyond) a common ionic threshold.
| Metric |
Default Setting |
Meaning |
| Nonpolar threshold |
< 0.40 |
Δχ below this is treated as essentially even electron sharing. |
| Polar threshold |
< 1.70 |
Between the two thresholds, bonds are increasingly polar covalent. |
| Model for % ionic |
Pauling (k = 0.25); alt k = 0.23 |
Choose the empirical constant used in the formula below. |
Percent ionic character formula
A classic empirical estimate of ionic character uses an exponential form linked to Δχ:
Ionic % = (1 − e−k·(Δχ)2) × 100
Here k is an empirical constant. In the original Pauling‑style estimate,
k ≈ 0.25 works well for many main‑group examples; some texts prefer k ≈ 0.23.
This calculator lets you toggle between the two to illustrate how sensitive the percentage is to the chosen constant.
Remember that “percent ionic” is a model‑based descriptor rather than a strict observable and should be used for
qualitative comparison, not as an absolute truth for any one bond.
Worked examples (Pauling scale)
| Bond |
χ(A) |
χ(B) |
Δχ |
Type (default thresholds) |
Ionic % (k = 0.25) |
| C–H |
2.55 |
2.20 |
0.35 |
Nonpolar covalent (very slight polarity) |
≈ 3.0% |
| O–H |
3.44 |
2.20 |
1.24 |
Polar covalent |
≈ 31.9% |
| Na–Cl |
0.93 |
3.16 |
2.23 |
Ionic |
≈ 71.1% |
| H–F |
2.20 |
3.98 |
1.78 |
Very polar covalent (near ionic boundary) |
≈ 54.8% |
Scales and data notes
The Pauling scale (dimensionless) is the most widely taught and is the default here. The Allen scale is derived from
average valence‑state ionization energies and often assigns values to noble gases; Mulliken values are based on
ionization energy and electron affinity averages; and Allred‑Rochow estimates electron‑attracting power from
effective nuclear charge and covalent radius. Different scales can rank certain elements differently—use the
Across Scales Comparison chart to see those divergences. For some heavy or synthetic elements, values may be
missing or uncertain; those entries appear as N/A and are excluded from heatmap coloring and ranking unless you
provide a dataset extension via the JSON export/import workflow.
Finally, keep in mind that electronegativity is a useful heuristic, not a complete theory of bonding. Molecular shape,
resonance, polarization, and environment all influence real charge distribution. Use Δχ and the percent‑ionic estimate
as a first pass, then refine with experimental data or higher‑level calculations when needed.