aktinoidiset

Aktinoidiset, also known as actinides, are a series of 15 metallic chemical elements in the periodic table, ranging from actinium (atomic number 89) to lawrencium (atomic number 103). These elements are characterized by the filling of the 5f electron shell. They are all radioactive, with no stable isotopes. The name "actinide" comes from actinium, the first element in the series.

The actinides are typically found in the f-block of the periodic table, although some classifications place them below the main body of the table, alongside the lanthanides. All actinides are metals, and they exhibit a wide range of chemical properties. Many are silvery-white and highly reactive. Due to their radioactivity, they are often handled with extreme caution and in specialized facilities.

The most well-known actinide is uranium, which is used as fuel in nuclear power plants and in nuclear weapons. Plutonium is another significant actinide, also used in nuclear reactors and weapons, and is produced artificially. Thorium is also found naturally and has potential applications in nuclear energy. The heavier actinides, from neptunium onwards, are generally synthetic and are produced in nuclear reactors or particle accelerators. Their study is crucial for understanding nuclear physics, chemistry, and the development of new technologies.