→ The d-block occupies the large middle section flanked by s- and p-blocks in the periodic table.
→ The name 'transition' given to the elements of d-block is only because of their position between s- and p-block elements, and their properties is transition between s and p block elements.
→ The d-orbitals of the penultimate energy in their atoms receive electrons giving rise the three rows of the transition metals, ie., 3d, 4d and 5d.
→ The fourth row of 6d is still incomplete.