Actinides

The actinides are a series of fifteen metallic elements, from actinium (Ac, Z = 89) to lawrencium (Lr, Z = 103). Like the lanthanides, they are displayed in a separate row beneath the main periodic table. The actinides fill the 5f electron subshell and include some of the most consequential elements in human history — uranium and plutonium among them.

---

Position in the Periodic Table

The actinides belong to period 7 and would sit between radium (Ra, Z = 88) and rutherfordium (Rf, Z = 104) in a full-length table. They are named after actinium, the first element in the series.

---

The Actinide Elements