The process of naming new chemical elements often honors famous scientists, references mythological figures, or describes a particular property of the substance. Among the many elements named after places, one stands out for taking its name from an entire landmass, leading to the question of which element is named after a continent.
The Element Named After a Continent
The element named after a continent is Americium (Am, atomic number 95). This synthetic, highly radioactive element is classified as a transuranic actinide metal, meaning it sits beyond uranium on the periodic table. Americium is named after The Americas and is the only element named after this vast geographical region. It is rarely found in nature, existing only in trace amounts in uranium minerals, and is primarily recognized for its use in common household smoke detectors.
The Story of Its Synthesis
Americium was first intentionally synthesized in late 1944 by a team of American scientists working at the Metallurgical Laboratory at the University of Chicago, part of the wartime Manhattan Project. The key figures were Glenn T. Seaborg, Ralph James, Leon Morgan, and Albert Ghiorso. Americium was the fourth transuranic element discovered, following neptunium, plutonium, and curium.
The element was produced through successive neutron capture reactions inside a nuclear reactor. Scientists bombarded plutonium-239 with neutrons, producing plutonium-240, which captured another neutron to become plutonium-241. Plutonium-241 subsequently underwent beta decay, transforming its nucleus to create americium-241.
The initial discovery was kept secret due to its connection to the war effort, but it was later declassified. The difficult chemical separation of the element, which researchers jokingly called “pandemonium,” prompted Glenn Seaborg to rethink the periodic table. He realized that elements like americium behaved chemically like the lanthanides, leading him to propose the actinide series, which organizes the heaviest elements into a separate row.
The Logic Behind the Name
The rationale for naming Americium was a deliberate parallel drawn from the periodic table. The name was chosen by analogy to europium (Eu, atomic number 63), which sits directly above americium in the group arrangement. Europium, a lanthanide, had been named after the continent of Europe.
Because americium was chemically analogous to europium, the discoverers used a geographical naming convention to highlight this relationship. Just as europium was named after Europe, americium was named after The Americas, the continent where the discovery was made. This established a systematic, geographical link between the two chemically similar elements.
Elements Named After Places and Regions
While Americium is the only element named after an entire continent, naming elements after specific geographical locations is a well-established tradition. The International Union of Pure and Applied Chemistry (IUPAC) allows elements to be named after a place or country, creating numerous “toponyms” on the periodic table.
Examples of this convention include elements named after countries, such as Germanium (Germany), Francium (France), and Polonium (Poland). Other elements honor cities or regions, often the site of their discovery, like Berkelium (Berkeley, California) and Californium (California). Elements like Dubnium (Dubna, Russia) and Darmstadtium (Darmstadt, Germany) continue this practice.