Unpentunium

Unpentunium is the temporary systematic name for the hypothetical chemical element with atomic number 155, derived from the digits of its atomic number.

Atomic number: The number of protons in an atom’s nucleus, which defines the chemical element. The number 155 identifies the element that the systematic name denotes.
Extended periodic table: A proposed arrangement of elements beyond those currently established, often including predicted superheavy elements. It provides frameworks for considering where element 155 might fit.
Unpenthexium: The former systematic name for element 156, now officially named livermorium. Its replacement shows how a provisional name gives way after an element is recognized.
Nuclear stability: The tendency of an atomic nucleus to persist rather than decay or undergo fission. Whether a nucleus with 155 protons could persist is unresolved.
Chemical element: A pure substance whose atoms all have the same number of protons. Unpentunium would be an element if atoms with 155 protons were established.
Superheavy element: A chemical element with a very high atomic number, generally beginning with rutherfordium at 104. If produced, element 155 would be far beyond the recognized superheavy elements.
Unquadpentium: The systematic name for hypothetical element 145, formed from the digits of its atomic number. It uses the same naming method for a different unconfirmed element.
Nuclear shell model: A model of nuclei in which protons and neutrons occupy quantized energy levels. Shell-model predictions inform estimates of stability at extreme proton numbers.
IUPAC systematic element name: A provisional element name formed from standardized numerical roots and a conventional ending. Unpentunium follows this naming system for element 155.
Island of stability: A predicted region of enhanced nuclear stability among superheavy isotopes. Predictions about nuclear stability shape speculation about extremely high atomic numbers.

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UnquaduniumRelated: It applies the same naming rules to a hypothetical element farther along the sequence.