The orbital where the last electron enters defines the block in the periodic table where the elements belong to:
| Atomic number | Block | Electronic Configuration |
| 37(K) | s-block | [Ar]4s1 |
| 78(Pt) | d-block | [Xe]4f145d96s1 |
| 52(Te) | p-block | [Kr]4d105s25p4 |
| 65(Tb) | f-block | [Xe]4f96s2 |