| 释义 |
ac·tin·i·um
\akˈtinēəm\ noun
(-s)
Etymology: New Latin, from actin- + -ium; from the darkening effect of light on some zinc sulfide
1. : a supposed chemical element once thought to occur in commercial zinc
2. : a radioactive trivalent metallic element resembling lanthanum in chemical properties formed by alpha radiation from protactinium and found especially in pitchblende — symbol Ac; see actinide series, actinium series; element table |