[SOLVED] Atomic radii I need to know precisely how the average atomic radii are calculated or found? I would expect it to be on the average contents of an experimental sample with adjustment for differing percentages. This would mean that isotopes missing from the sample are not included in the calculation of the average. Alternatively it could be adjusted for all known isotopes. The precise figures and method are required to enable a check on my work on the atomic radii of istopes, which is still ongoing thanks to the replies to previous questions. There was three different answers to my earlier questions- a) all isotopes have the same radii, determined by the number of electron shells (same for all isotopes of a given element). b)Isotopes have different radii, but the difference is to small to measure. c) It is not possible to determine whether or not there is any difference. I am still hopeful that a table of isotope atomic radii is achievable.