Question

if the radius of Mg2+ ions, Cs+ ions, S2- ions are 0.65 angstrom, 1.69​angstrom, 1.40​angstrom respectively then calculate the coordination no. of cation in crystals of MgS, MgO.
need the answer urgently!!!

Answer 1

We cannot calculate the coordination number for MgO as radius of O2- is not given.
For calculating the coordination number of MgS, at first we will calculate the radius ratio:
Radius Ratio = Radius of cation/ Radius of anion
Radius ratio for MgS = Radius of Mg2+ / Radius of S2-
                                  = 0.65 A/ 1.40 A
                                  = 0.464

If radius ratio falls in between 0.414 to 0.732, the coordination number is 6.
The radius ratio chart to find out coordination number