Question

there is not much difference of atomic size from cr to cu​

Answer 1

Cu is not a multiple of Cr, in fact some of the measurements are within a few percent of each other. I would say that there is not much difference. The empirical values seem to be within margin of error.

Answer 2

Answer:

Atomic size of Cr and Cu are about the same As Transition Elements are relatively because although the number of protons in the nucleus increase.

It mainly has complete additional elements have been added as 3d subshell.

Electrons in the 3d subshell contribute to the shielding effect as well as results in a relatively constant and more effective option as the nuclear charge.