4.The first ionization energy()of d-block elements 850 800 70 700 5th 650 4ch 00 550 00 解 RB The overall tendency is that values of I become slightly bigger from left->right in a row,while irregular in a group. The overall tendency is that values of I1 become slightly bigger from left → right in a row, while irregular in a group. 4. The first ionization energy(I1) of d-block elements