Estimate molecular distances with radii, bond order, and crystal inputs. Review corrections, compare methods, and export reliable bond summaries fast.
| Bond | Covalent Radius A (pm) | Covalent Radius B (pm) | Bond Order | Approx Length (pm) |
|---|---|---|---|---|
| H-H | 31 | 31 | 1 | 74 |
| C-C | 77 | 77 | 1 | 154 |
| C=C | 77 | 77 | 2 | 134 |
| C≡C | 77 | 77 | 3 | 120 |
| C=O | 77 | 66 | 2 | 123 |
1. Covalent method: Bond length is estimated from the sum of covalent radii, then adjusted for bond order, electronegativity difference, resonance, and temperature effects.
2. Ionic method: Bond length is estimated from cation and anion radii, then corrected for polarity and structural adjustments.
3. Crystal geometry method: Bond length is estimated from unit-cell edge multiplied by an appropriate geometry factor for the lattice.
Key relations:
These are practical estimation models. Actual bond lengths depend on hybridization, molecular environment, coordination, pressure, and experimental method.
Bond length is the average distance between two bonded atomic nuclei. It is usually reported in picometers or angstroms and depends on bond type, bond order, and surrounding structure.
Higher bond order usually pulls atoms closer together. Triple bonds are generally shorter than double bonds, and double bonds are shorter than single bonds.
Yes. The ionic method adds cation and anion radii, then applies simple corrections. It is useful for quick estimates in salts and crystal chemistry studies.
Electronegativity difference reflects bond polarity. Greater polarity can shift electron density and slightly alter the expected internuclear distance compared with a simple radii sum.
The result is an estimate. Real bond lengths depend on hybridization, resonance, coordination number, pressure, temperature, and the experimental technique used for measurement.
Picometers are common in chemistry tables. Angstroms are popular in structural chemistry and crystallography. Nanometers are convenient for broader nanoscale comparisons.
If you enter a measured value, the calculator reports deviation and percent error. This helps compare theoretical estimates with published or experimental data.
Yes, for some solids. When crystal structure is known, a unit-cell edge and geometry factor can estimate neighbor distances in a fast, practical way.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.