posted by Ivy .
Which one in this pair has the larger radius? Explain
a. Calcium atom or calcium ion
b. Aluminum ion or Magnesium ion
Calcium ion has the two outside electrons removed; therefore, it should be smaller than the atom.
Aluminum ion has a +3 charge on it while Mg ion has just +2; therefore, the protons in the nucleus of Al exert a greater pull on its electrons than Mg and the Al ion should be smaller.