The actinide series consists of 15 metallic elements from actinium (Ac) to lawrencium (Lr) in the periodic table. These elements are characterized by their filling of the 5f electron orbital.
Lanthanide Series: A group of elements from lanthanum (La) to lutetium (Lu), often known as rare earth metals, characterized by filling of the 4f electron orbital.
Transuranium Elements: Elements with atomic numbers greater than uranium (92), all of which are synthetic and include some members of the actinide series.
Radioactivity: The process by which unstable atomic nuclei lose energy by emitting radiation; a common property among many actinides.