# Question #80ff6

May 8, 2015

As far as I know, the picometer is currently being used as the SI unit for atomic radii.

A picometer is equal to ${10}^{- 12} \text{m}$.

The more traditional unit used was the angstrom, for which you have

$\text{1 angstrom" = 10^(-10)"m}$

Keep in mind, however, that angstroms are not SI units.

You'll sometimes see atomic radii expressed in nanometers, for which

$\text{1 nm" = 10^(-9)"m}$

However, nanometers are not used as often as picometers for atomic radii.