Atomic No. Name Symbol 89 Actinium Ac 90 Thorium Th 91 Protactinium Pa 92 Uranium U 93 Neptunium Np 94 Plutonium Pu 95 Americium Am 96 Curium Cm 97 Berkelium Bk 98 Californium Cf 99 Einsteinium Es 100 Fermium Fm 101 Mendelevium Md 102 Nobelium No 103 Lawrencium Lr The actinoid (according to IUPAC terminology) (previously actinide) series encompasses the 15 chemical elements that lie betw… (More on Actinides)