Polarising Ability of Cations: Transition vs. Noble Gas Configs

[konichiwa2x]

For cations of the same size and charge, the one with electronic configuration (n-1)d^n ns^o, typical of transition metals, is more polarising than the one with a noble gas configuration, ns^2 np^6, typical of alkali and alkaline Earth metal cations.
Can someone please explain why this is so?

 

[Gokul43201]

It follows from an understanding of the term 'polarizing power' or 'polarizing ability'. What does this term mean?

PS: Note that, by our guidelines, we can not help with standard textbook type questions unless you first show some of your thoughts/effort.

 

[konichiwa2x]

No, my doubt is regarding what is trying to be said in the above lines. Does it mean that an element having a pseudo noble gas configuration is more polarising than a one with a noble gas configuration?? I think 'n' was not meant to take the same value in both the electronic configurations. The atomic radius of Na+1ion is 0.95 A and that of Cu+1 is also the same. I think what was meant is the book is, for two ions of the same size and charge, one with a pseudo noble gas configuration will be more polarising than the cation with a noble gas configuration. So I suppose, CuCl is more covalent than NaCl.

by the way, can you please explain what polarising ability is? I thought the shared pair of electrons in a molecule would always be attracted more to the anion as they are usually more electronegative. Please explain.