[peacefulltortoise]

I think radius of Na+ is smaller than Ne but my book shows the opposite way. Am I wrong or is my book wrong? I think it might because the different ways that people find out (calculate) atomic radius and ionic radius, is that right?

[Donaldson Tan]

Although both Ne and Na+ contains the same number of electron, Na+ nucleus contains a higher positive charge than that of Ne. This means stronger attraction between the valence shell electron and the positively charged nucleus, in the case of Na+, therefore the radius of Na+ will be less than that of Ne.