Element category
Actinides
The actinides are the fifteen metals from actinium to lawrencium that fill the 5f subshell, shown as the second separate row beneath the main table. Every member is radioactive; only thorium and uranium occur in quantity in nature, and the elements beyond uranium are made in reactors and accelerators. The early actinides show a wider spread of oxidation states than the lanthanides above them.
At a glance
- Elements
- 15
- Atomic numbers
- 89 to 103
- Blocks
- f-block, d-block
- Period
- 7
- Phase at STP
- solid (11)
Shared properties
- Fill the 5f subshell and form the second detached row of the table
- All members are radioactive; most beyond uranium are synthetic
- Early members show several oxidation states, unlike the mostly +3 lanthanides
- Thorium, uranium and plutonium serve as nuclear fuels