Within group 9 of the periodic table, IE1 for Co is greater than IE1 for Rh. However, in group 10, IE1 for Ni is smaller than IE1 for Pd. Compare the ground state electron configurations of these elements to account for the difference. The groud state electron configurations of Rh and Pd are given as follows:
Rh: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s1 4d8
Pd: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 4d10
Make sure to compare Co to Rh and Ni to Pd.