The fifteen elements with atomic numbers 89 to 103, which includes Actinium (Ac), Thorium (Th), Uranium (U), Neptunium (Np), Plutonium (Pu), Americium (Am), Californium (Cf), Einsteinium (Es) and Lawrencium (Lr), are known as what?
Actinoid series
actinoid series
actinoid series
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Actinoid series