The atomic radii of elements from Cr to Cu (i.e. Cr,Mn,Cu ) are very close to one another. This is due to effective screening of outer -electrons by the electrons of (n−1)d subshell. The reason for the anomalous increase in atomic radii towards the end of the series is predominant repulsion between the added electrons. Presence of completely filled -orbitals also decreases the force of attraction.