Which ion in each of the following pairs would you expect to be more strongly hydrated?

(a) Na+ or Mg2+

Why?

thanks!!

4 answers

If you are a water molecule you are polarized with the O end slightly negative and the H end slightly positive. Which would you be more highly attracted to, a +1 charge or a +2 charge?
what about when u are comparing the same charge

Be2+
Mg2+

or the same base element

Fe2+
Fe3+
It depends to a large extent on what you mean by STRONGLY hydrated. Is that the strength of the bond or the number of water molecules attracted?
In the case of Be ion vs Mg ion, the Be-H2O bonds probably are stronger because the Be ion is smaller thus the charge density is higher. However, since it is smaller (that is the Mg ion is larger), the Mg ion hydrates with 6 molecules H2O while the usual number for Be is 4.
In the case of iron(II) vs iron (III), the charge is higher on iron(III) wo it will more strongly attract water molecules.
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