KnowraActiniumLinked fromLinked fromThe 8 pages that link to Actinium, each with the reason it gives.All 8Broader topic 3Related 5ActinideBroader topic: Its name gives the series its name, though its placement among the actinides was established later.Actinide seriesBroader topic: It anchors the series at its lightest end.Group 3 elementBroader topic: It occupies Group 3 alongside lanthanum in the competing layout.