The actinide series, or actinoid series, includes the 15 metallic chemical elements with atomic numbers 89 to 103. The name “actinide” derives from the first element in the sequence, which is called actinium. The actinides are all unstable, meaning they decay and release radiation.
The longer-lived actinides have half-lives measured in millennia or even millions of years. Uranium is the most familiar actinide because it is the heaviest naturally-occurring element and is used in nuclear reactors and weapons.
The other actinides are less well known but are important in various industrial and scientific applications.
Actinium
Thorium
Protactinium
Uranium
Neptunium
Plutonium
Americium
Curium
Berkelium
Californium
Einsteinium
Fermium
Mendelevium
Nobelium
Lawrencium
Introduction Actinium is a rare-earth element that belongs to the family of actinides in the periodic table. The actinide series of elements is highly significant due to their radioactive properties. They comprise a group of 15 chemical elements that share the same chemical and physical properties. Fact Box Physical and Chemical Properties of Actinium … Read more
Uranium (U) Introduction Uranium is a chemical element with the atomic number 92 in the periodic table. This substance makes up about two parts per million of Earth’s crust. Uranium in the layers of Earth is as common as the elements tin, tungsten, and molybdenum. As a member of the actinide series of periodic table … Read more
Americium is a transuranic element with the symbol Am and atomic number 95 in the periodic table of elements that belongs to the family of actinides. This radioactive substance was discovered as the fourth synthetic transuranium element in the list of fifteen radioactive metallic elements that include actinium, thorium, protactinium, uranium, neptunium, plutonium, americium, curium, … Read more
Berkelium is a chemical element with the symbol Bk and the atomic number 97 in the periodic table of elements. Since it’s synthesized in a laboratory, berkelium is not found naturally in its elemental form in Earth’s crust. Being a member of the actinide family of periodic table elements, this radioactive metal shares the physical … Read more
Californium is a radioactive chemical element with the symbol Cf and atomic number 98 in the periodic table of elements. It’s a synthetically produced element, hence it cannot be found in Earth’s crust. Being a member of the actinides family of periodic table elements, californium’s molecular structure can be divalent or trivalent. Fact Box Chemical … Read more
Introduction Fermium is a chemical element with an atomic number of 100 in the periodic table of elements. Being a synthetically produced radioactive substance, this lanthanide does not exist naturally in Earth’s crust. This is the heaviest synthetically produced element that has been created by bombarding lighter elements with neutrons. Fact Box Chemical and Physical … Read more
Nobelium (No) Introduction Nobelium is a chemical element with the atomic number 102 in the periodic table. Since it’s a synthetically produced substance, element 102 cannot be found naturally in Earth’s crust. According to Mendeleev’s classification of elements, nobelium is a member of the actinides family of the periodic table. It has three valence electrons … Read more
Lawrencium (Lr) Introduction Lawrencium is a synthetic chemical element with atomic number 103 in the periodic table. This man-made radioactive actinide metal has not been detected in Earth’s crust yet. A member of the actinide series in the periodic table, lawrencium has three valence electrons on the outer shell that help element 103 participate in … Read more