+8 = 16 

ā

  1. (actinium,Ac)​化學元素原子序89。放射性元素銀白色自然界鈾礦共存硫化物化合物

actinium (chemistry)​
actinium
Actinium (Element 89, Ac)​ (S, Chem)​, Aktinium (S, Chem)​