f-block chemical elements

The actinide series is the 15 chemical elements between actinium and lawrencium on the periodic table. They have the atomic numbers between 89 and 103. The actinide series is named after actinium. All of the elements are radioactive. Uranium is the most common natural actinide, and thorium second.[1]

Location of actinides on the periodic table

The term ‘actinide series’ has been derived from the first element of the series, actinium. The symbol An is used while referring to any of the actinide series elements.

All actinide series elements are radioactive in nature, they release a large amount of energy on radioactive decay. Uranium and thorium are the most abundant naturally occurring actinides on earth, whereas plutonium is synthetically obtained.[2]

The actinide elements

Atomic Number Name Symbol Picture
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


  1. Anonymous (2018-04-19). "Properties of Actinide Materials under Extreme Conditions". EU Science Hub - European Commission. Retrieved 2021-11-11.
  2. "Actinide - an overview | ScienceDirect Topics". Retrieved 2021-11-11.