Element discovery

Element discovery is the experimental confirmation that a substance has an atomic nucleus with a previously unknown proton number. It establishes a new chemical element, often through detection of its characteristic decay or chemical behavior.

Atomic number: The number of protons in an atomic nucleus, which determines the chemical element. A new element is defined by a proton number not previously confirmed.
Technetium: The element with atomic number 43, first produced artificially and identified in 1937. Its identification established the first element discovered through deliberate nuclear synthesis.
Antoine Lavoisier: An eighteenth-century French chemist who helped establish modern chemical nomenclature and an operational definition of elements. His classification made systematic claims about elemental substances more precise.
Island of stability: A predicted region of superheavy nuclei with longer lifetimes than neighboring nuclei. Longer-lived isotopes could make new elements easier to detect and characterize.
Nuclear reaction: A process in which atomic nuclei collide or transform, changing their composition or energy. Many new elements are made by inducing fusion or particle capture in target nuclei.
Astatine: The radioactive halogen with atomic number 85, first produced and identified in 1940. Its discovery showed that an element missing from nature could be made in a particle accelerator.
Humphry Davy: An English chemist who isolated several elements using electrolysis in the early nineteenth century. His experiments exemplify discovery by separating previously unknown elements from compounds.
Superheavy element: A chemical element with atomic number greater than 103. Current discovery efforts focus on producing and confirming members of this broad class.
Particle accelerator: A machine that uses electromagnetic fields to propel charged particles to high energies. Accelerators supply the projectile nuclei used to synthesize many new elements.
Promethium: The lanthanide with atomic number 61, identified among products of uranium fission in 1945. Its discovery relied on isolating and identifying a rare fission product.

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