Periodic table extension

Periodic table extension is the effort to predict and investigate elements beyond the currently confirmed periodic table. It combines nuclear physics, chemical theory, and searches for short-lived atomic nuclei.

Island of stability: A predicted region of superheavy nuclei whose enhanced stability may give them longer half-lives than nearby isotopes. It is the most prominent prediction about whether some undiscovered superheavy elements could be comparatively long-lived.
Heavy-ion fusion: A nuclear reaction in which accelerated heavy nuclei collide and sometimes fuse into a heavier nucleus. It is the main method used to synthesize the heaviest known elements and test routes to heavier ones.
Dmitri Mendeleev: A Russian chemist who formulated a periodic table and predicted properties of then-undiscovered elements. His successful predictions established the precedent for using periodic order to anticipate unknown elements.
Superheavy element: An element with a very high atomic number, usually used for elements with atomic number 104 or greater. These nuclei are the immediate targets of experiments seeking to extend the confirmed table.
Periodic table: A tabular arrangement of chemical elements ordered by atomic number and recurring chemical properties. The confirmed table ends where experimental evidence stops; proposed extensions go beyond that boundary.
Nuclear drip line: The boundary beyond which a nucleus cannot retain an additional proton or neutron. Drip lines constrain which proton-rich and neutron-rich isotopes of future elements can exist.
Cold fusion (superheavy-element synthesis): A superheavy-element production method that fuses a lead or bismuth target with a medium-mass projectile. This reaction strategy enabled several elements near the current end of the table.
Transuranium element: A chemical element with an atomic number greater than uranium’s 92. The modern extension effort continues the search for elements beyond the naturally occurring heavy elements.
Element 119: The proposed chemical element with atomic number 119, currently unconfirmed. Its synthesis would begin a new period in the periodic table.
Nuclear liquid-drop model: A model that treats an atomic nucleus as a drop of nuclear fluid with collective properties. Its predictions of fission compete with shell-based explanations of superheavy-nucleus survival.

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