Oganesson: the last chemical element discovered

 Unquestionably, the periodic table of elements stands as one of humanity's most significant scientific accomplishments. The artistic arrangement of chemical elements in groups and periods echoes the splendid intricacy of nature. Originated by Russian chemist Dmitry Ivanovič Mendeleev in 1869, this table initially had numerous blanks, filled over time with advancements in chemistry and physics, the most recent being the addition of oganesson. The systematic organization of these elements, based on atomic number, is segmented into groups (vertical columns) and periods (horizontal rows).

Understanding Atoms and Chemical Elements

A chemical element is a pure chemical substance composed of atoms with an identical number of protons. In a simplified perspective, an atom consists of subatomic particles: protons (with positive charge) and neutrons (without charge) in the nucleus, and electrons (with negative charge) circling it. While electrons participate in chemical reactions, protons and neutrons are integral to nuclear reactions. Important definitions for comprehending the atoms and reactions involved include: atomic number "Z" (the quantity of protons in the nucleus) and mass number "A" (the sum of protons and neutrons in the nucleus). A nuclide can be defined as a nuclear species characterized by a specific atomic number and mass number.

The journey to the current periodic table, ordered by ascending atomic number, was intricate and lengthy. A key breakthrough leading to the current arrangement was the discovery of transuranic elements, which have atomic numbers exceeding that of uranium, specifically 92. Elements with atomic numbers above 104 are designated as superheavy elements. Due to their instability, transuranic and superheavy elements, which are not found in the solar system, are synthesized in labs.

Manufacturing of Transuranic Elements

Typically, the synthesis of transuranic elements involves:

• Neutron capture reactions: This process involves the absorption of neutrons within nuclear reactors by nuclides, which subsequently transmute (an unstable nuclide transforms into one of greater stability).
• Reactions prompted by accelerated charged particles: In this method, atomic nuclei are sped up (as projectiles) and made to collide with other nuclei (targets). The size and energy of the projectile nuclei can differ and are accelerated using specific devices known as "particle accelerators."

Unlocking the Secrets of Oganesson

In 2002, an international collaboration of scientists from the Joint Institute for Nuclear Research in Russia and Lawrence Livermore National Laboratory in the US, spearheaded by Russian nuclear physicist Yuri Oganessian, conducted groundbreaking research. They collided californium-249 atoms with calcium-48 atoms, yielding atomic masses of 294.

249Cf + 48Ca → 294Og + 3n

Their experiments led them to conclude the synthesis of a superheavy element with an atomic number of 118, which was later christened as oganesson (Og) in tribute to Professor Yuri Oganessian. The International Union of Pure and Applied Chemistry (IUPAC) and the International Union of Pure and Applied Physics (IUPAP) validated the discovery of this new element in 2015. Oganesson, a noble gas, completes the seventh group of the periodic table. It has a fleeting half-life of 0.7 milliseconds and, at present, its applications remain purely academic and experimental.

The uncovering of oganesson not only filled in a missing piece of the periodic table but also added another layer to our understanding of the physical laws shaping the behavior of matter. Furthermore, these advancements are encouraging chemists and physicists to investigate the hypothesized "island of stability"—a term referring to the potential existence of undiscovered, highly stable chemical elements.