Actinide

Some metals are very special.

They give off energy. This energy is called radiation. Most of these metals are not found in nature.

People must make them in labs. Two metals, thorium and uranium, are in the ground.

Another metal is in smoke detectors. It helps keep your home safe. These metals are part of a big family.

The actinides are a family of metals. This group has at least 14 elements. They go from number 89 to 102. Most of these metals are very rare. They do not occur in nature. Scientists must make them in labs.

They make them by hitting atoms with small parts. They might use neutrons or charged particles. This is a way to build new elements.

All actinides are radioactive. This means they give off energy. We call this energy radiation. Only two are found in large amounts on Earth. These are thorium and uranium. Uranium and thorium are used in nuclear reactors. They are also used in nuclear weapons. Some actinides have other uses. For example, americium is used in smoke detectors.

This helps keep homes safe from fire. Most of the other elements in this family are purely synthetic. This means people make them from scratch.

The actinides are a special family of metallic elements. This group includes at least 14 different elements. They are numbered from 89 to 102 on the periodic table. The series starts with actinium and goes through nobelium. Element 103, lawrencium, is also often included in this group. These elements are very important to science. They help us understand how atoms and energy work.

Most actinides are made by people in labs. This is because many are purely synthetic. Scientists create them through a thing called transmutation. They do this by bombarding atoms with small particles. For example, they might hit uranium with neutrons.

This process can turn one element into another. They also use particle accelerators to hit atoms with charged particles. This method helps them make even heavier elements like nobelium. These methods allow us to build new parts of the periodic table.

Finding these elements took a long time. Martin Heinrich Klaproth found uranium in 1789. He found it in a mineral called pitchblende. Later, Friedrich Wöhler found thorium in 1827. Jöns Jacob Berzelius isolated the metal thorium in 1828. He named it after the Norse god Thor.

In 1940, Edwin McMillan and Philip Abelson discovered neptunium. This was the first transuranium element made by humans. Glenn Seaborg and his team at Berkeley later discovered many more.

There are many specific facts about these metals. All actinides are radioactive. This means they release energy as they decay. Only thorium and uranium are found in large amounts on Earth. Most other actinides are very rare or do not exist in nature. For instance, americium is used in modern smoke detectors.

Uranium and plutonium are also used in nuclear reactors. Scientists use these elements to study how energy is released. These numbers and names help us map the tiny world of atoms.

You can see these elements in your own life. The smoke detector in your hallway uses americium.

This keeps your home safe from fire. Some of these elements are also used to make power in reactors.

Even though you cannot touch them, they are all around us. They exist in the rocks of the Earth or in the machines we build. Understanding them helps us use energy in new ways. The study of actinides connects deep history to our modern world.

The actinide series is a group of metallic chemical elements. This series includes at least 14 elements with atomic numbers from 89 to 102. These elements range from actinium to nobelium. Scientists also often include lawrencium, which is element 103, in this group.

The series is named after its first element, actinium. In chemistry discussions, the symbol An is sometimes used to refer to any actinide. While the term "actinide" is very common, the IUPAC Red Book suggests using "actinoid" instead. This is because the suffix "-ide" usually describes a negative ion.

Most actinides are f-block elements. This means they involve the filling of the 5f electron shell. However, some atoms have unusual configurations. Because of interelectronic repulsion, many atoms fill the 6d shell instead. This makes their atomic and ionic radii very large. They also show a very wide range of physical properties. Compared to the lanthanide series, actinides show much more variable valence. Valence refers to the number of electrons an atom can use for bonding.

Within the series, elements can be grouped by their position. The transuranium elements are those that follow uranium in the periodic table. The transplutonium elements are those that follow plutonium. All actinides are radioactive. This means they release energy through a process called radioactive decay. Because of their long half-lives, only thorium and uranium are found in large amounts on Earth. Other actinides are either found in tiny trace amounts or are purely synthetic.

Finding these elements was a long process of discovery. Martin Heinrich Klaproth identified uranium in 1789 from pitchblende ore. He named it after the planet Uranus. In 1827, Friedrich Wöhler discovered thorium oxide in Norway. Jöns Jacob Berzelius later isolated the metal thorium in 1828. He named it after the Norse god Thor.

In 1899, André-Louis Debierne discovered actinium. Later, in 1940, Edwin McMillan and Philip H. Abelson produced neptunium. This was the first transuranium element produced synthetically.

Scientists use different methods to create synthetic actinides. One way is to bombard lighter elements with neutrons. This is often done in nuclear reactors. For example, bombarding uranium-238 with neutrons can create plutonium-239. This reaction was used at the Hanford Site during the Manhattan Project. Another method uses particle accelerators. This method involves bombarding atoms with accelerated charged particles. This technique is useful for making elements heavier than plutonium. For instance, nobelium was made by bombarding uranium-238 with neon-22.

Actinides have many important uses in our modern world. Uranium and thorium are used in nuclear reactors to produce energy. Plutonium is also a critical element used in nuclear weapons. Some actinides are used in everyday technology. For example, americium is used in the ionization chambers of most modern smoke detectors.

Even though many are man-made, they play a huge role in science. They help us understand how energy is released from the nucleus of an atom.

The study of actinides changed how we see the periodic table. In 1934, Enrico Fermi suggested transuranium elements might exist. In 1944, Glenn Seaborg formulated the "actinide hypothesis." This idea helped scientists realize these elements formed a unique family.

Before this, many thought these elements were just regular 6th-period metals. Now, we know they form their own special row. This understanding connects the study of tiny atoms to large-scale energy production.