Most chemists thought the lanthanides and actinides could be inserted in the sixth and seventh rows, but no, they're just floating down at the bottom with lots more undiscovered elements all around them.

"Chemistry Nobel", by Randall Munroe, licensed under Creative Commons Attribution-NonCommercial 2.5 License

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Most chemists thought the lanthanides and actinides could be inserted in the sixth and seventh rows, but no, they're just floating down at the bottom with lots more undiscovered elements all around them.