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Which elements belong to the actinoid series?
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periodic table
Modern version of the periodic table of the elements. To learn an element's name, atomic number, electron configuration, atomic weight, and more, select one from the table.
The actinoid series (also known as the actinides) consists of 15 consecutive chemical elements in the periodic table with atomic numbers 89 through 103.1
The elements belonging to this series are:
- Actinium (89)
- Thorium (90)
- Protactinium (91)
- Uranium (92)
- Neptunium (93)
- Plutonium (94)
- Americium (95)
- Curium (96)
- Berkelium (97)
- Californium (98)
- Einsteinium (99)
- Fermium (100)
- Mendelevium (101)
- Nobelium (102)
- Lawrencium (103)
These elements are characterized by the filling of the 5f electron orbital. While the International Union of Pure and Applied Chemistry prefers the term "actinoid," the name "actinide" is also commonly used. All members of the series are radioactive, and most are synthetic, with only actinium, thorium, protactinium, and uranium occurring in nature to any significant extent.231