Atoms of transition elements such as Sc, Ti, V, Cr, Mn, Fe, Ni, Cu have partially filled d orbital • They have irregular configurations (different from the predicted one) because they tend to shift electrons to acquire a more stable configuration
The predicted configuration for 24Cr is Cr : 1s2 2s2 2p6 3s2 3p6 4s2 3d4 But the actual electronic configuration for Cr is Cr : 1s2 2s2 2p6 3s2 3p6 4s1 3d5
