What is the difference between crystal radius and ionic radius? For $\ce{NaCl}$ for example the ions combine to a crystal, and I would have guessed they are equal. But I then found an example of data, where they are not.

I am aware that ionic radius is the radius of an atom's ion. Quite simple. So what is crystal radius?

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    $\begingroup$ I have found two different uses of the term "Crystal Radius." First is Linus Pauling's use of Crystal Radaii, which refers to ions that are free and not part of a crystal. The second is used to describe some parameters of the flame fusion crystal growth this paper, which would seem to be very much incorporated into the crystalling structure. This seems to be a rarely encountered term. Where did you encounter it? $\endgroup$
    – Dale
    May 30, 2015 at 23:55
  • $\begingroup$ Similar question: researchgate.net/post/… $\endgroup$
    – Dale
    May 30, 2015 at 23:57
  • $\begingroup$ There is a table of "Pauling Empirical Crystal Radiuses", which cites the following sources: Galasso, Francis S. Structure and Properties of Inorganic Solids. Oxford: Pergamon Press, 1970. Pauling, Linus. The Nature of the Chemical Bond, 3rd edition. Ithaca, NY: Cornell University Press, 1960. Rohrer, Gregory S. Structure and Bonding in Crystalline Materials. Cambridge: Cambridge University Press, 2001. $\endgroup$
    – Dale
    May 31, 2015 at 3:06

1 Answer 1


To quote Erik Rakovský · 30.73 · 54.96 · Comenius University in Bratislava (from this discussion on researchgate)

Shannon published simultaneously two sets of ionic radii. So called "effective ionic radii" were made consistent with Pauling's r($\mathrm{O_2^-}$)=140 pm. "Crystal radii" are using Shannon's value r($\mathrm{O_2^-}$)=126 pm.


  • $\begingroup$ Could you please summarise the content of these links? $\endgroup$
    – Gerhard
    Feb 3, 2016 at 0:57
  • $\begingroup$ @Gerhard The description is already above each link respectively. $\endgroup$
    – Dale
    Feb 4, 2016 at 4:11
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    $\begingroup$ This answer would have been more helpful if you would have explained what all there is in those links and then provided them as source. Just saying. $\endgroup$
    – Quark
    Feb 4, 2016 at 7:35
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    $\begingroup$ @Dale Only If I understood what the correct answer is. Haha. $\endgroup$
    – Quark
    Feb 5, 2016 at 20:33
  • 3
    $\begingroup$ People come to SE for answers, not for links. $\endgroup$
    – Quark
    Feb 5, 2016 at 20:34

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