Actinium
Emergence definition
Actinium is a substance that undergoes change, resulting in a transformation of state or condition, driven by energy and occurring over a sequence of events, and is classified as a chemical element with the symbol Ac and atomic number 89.
Wiktionary senses
Historical origin
Prerequisite chain
Neighborhood
In other languages
Prerequisites
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actinium requires understanding change as a foundational concept
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actinium requires understanding substance as a foundational concept