Samarium has 62 electrons arranged as 2, 8, 18, 24, 8, 2 across 6 shells, which is why it sits in period 6.
Start from the previous noble gas core, written in square brackets, then add the remaining electrons in filling order. For samarium that gives [Xe] 4f6 6s2.
| Atomic number | 62 |
| Symbol | Sm |
| Atomic mass | 150.36 u |
| Group | f-block (no group number) |
| Period | 6 |
| Block | f-block |
| Category | Lanthanide |