Input interpretation
period 1 elements | atomic diameter
Results
hydrogen | 50 pm (picometers) helium | 62 pm (picometers)
period 1 elements | atomic diameter | 56 pm (picometers) (median)
Relative values
| visual | ratios | | comparisons hydrogen | | 0.8 | 1 | 19% smaller helium | | 1 | 1.2 | 24% larger
Plot
Plot
Periodic table location
Periodic table location
Atomic radii properties
| hydrogen | helium atomic radius (empirical) | 25 pm | atomic radius (calculated) | 53 pm | 31 pm covalent radius | 31 pm | 28 pm van der Waals radius | 120 pm | 140 pm
Units
Unit conversions for median atomic diameter 56 pm
0.056 nm (nanometers)
5.6×10^-11 meters
2.2×10^-9 inches
0.56 Å (ångströms)
Comparisons for median atomic diameter 56 pm
≈ (5×10^-4 to 0.8) × diameter of a molecule ( 0.74 to 1000 Å )
≈ 0.9 × atomic diameter of helium (the smallest atom) ( ≈ 62 pm )
≈ 1.1 × atomic diameter of hydrogen ( ≈ 50 pm )