Actinoid Apr 2026
Their chemical behavior is defined by electrons progressively filling the 5f orbital.
The actinoids (or actinides) are a series of ranging from atomic numbers 89 to 103. Named after their first member, actinium , these elements form the lower row of the f-block. Atomic Range: Actinium ( ) to Lawrencium ( actinoid
) occur in significant quantities in nature; most others are man-made (synthetic). ✨ Key Properties actinoid