11. Most of the samples tested positive for actinium -227, the workers were told. 12. The actinium -225 eventually becomes harmless and remains in the body, he said. 13. The actinide series derives its name from the first element in the series, actinium . 14. The abundance of actinium in the Earth's crust is only about 5 %. 15. Actinium is likely to be one of two elements that will next recieve a picture.16. Once inside, the alpha particles radiated from the actinium -225 will kill the cell. 17. Owing to its scarcity, high price and radioactivity, actinium has no significant industrial use. 18. The rare oxidation state + 2 is only known for actinium dihydride ( AcH 2 ). 19. The actinium -225 is made by the irradiation of radium-226 with a cyclotron. 20. In 1939, Perey discovered the element francium by purifying samples of lanthanum that contained actinium .
