Question

Arrange the following in increasing order of the atomic sizes and give reasons

Na⁺ , Mg²⁺ , Al³⁺ , F^- , O^2- , C^4-

Answer 1

C4- with atomic number 6 has 6+4= e
O2- witha tomic no. 8 has 8+2 = 10 electrons
F- with atomic no. 9 has 9+1= 10 electrons
Na+ with atomcatomic no. 11 has 9-1= 10 electrons
Mg2+with atomcatomic no. 12 has 12-2= 10 electrons
Al3+with atomcatomic no. 13 has 13-3= 10 electrons
Since all these ions have 10 electrons in their shell therefore these are isoelectronic speicies
The more + the charge, the smaller the ionic radius. Remember that - means adding electrons. These electrons go in the outermost shells. Also, when an atom loses electrons, it clings ever more tightly to the ones it has left, further reducing the ionic radius. therefore the order of ionic radii will be →

AL3+ Mg2+ Na+ F- O2- C4-increasing order