Where are the actinides placed on the periodic table?
Quick Answer
They are typically shown in a separate row below the lanthanides. The actinide series runs from actinium to lawrencium, elements 89 through 103.
The Full Story
The actinides are the elements with atomic numbers 89 through 103, starting with actinium and ending with lawrencium. Like the lanthanides, they are usually separated into a row beneath the main table, even though they belong in period 7. Many actinides are radioactive, and several are synthetic, including americium, curium, and einsteinium. Uranium and thorium are the best-known naturally occurring actinides and are central to nuclear energy and geochemistry.
Key Facts
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"The periodic table’s most radioactive family lives in a hidden row"
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