Consider the following species : N3-, O2-, F-, Na+, Mg2+ and Al3+
(a) What is common in them?
(b) Arrange them in the order of increasing ionic radii.
(a) Each one of these ions contains 10 electrons and hence all are isoelectronic ions.
(b The ionic radii of isoelectronic species increase with a decrease in the magnitudes of nuclear charge. The arrangement of the given species in order of their increasing nuclear charge is as follows:
N3-< O-2<F-<Na+<Mg2+<Al3+
In each of the following pairs, which species has a larger size? Explain.
(i) K or K+
(ii) Br or Br-
(iii) O2- or F-
(iv) Li+ or Na+
(v) P or As
(vi) Na+ or Mg2+
Which of the following species will have the largest and the smallest size?
Mg, Mg2+, Al, Al3+.
What do you understand by isoelectronic species? Name a species that will be isoelectronic with each of the following atoms or ions.
(i) F- (ii) Ar (iii) Mg2+ (iv) Rb+
Give the formula of a species which will be isoelectronic with the following atoms or ions:
(i) Na2+
(ii) Cl-
(iii) Ca2+
(iv) Rb+.