Unun1

Unun1 is a placeholder name for a chemical element. The International Union of Pure and Applied Chemistry, or IUPAC, assigns temporary names to elements that have been synthesized but not yet officially recognized or named. These temporary names are based on the element's atomic number.

The name "unun1" is derived from the Latin words for its atomic number. The atomic number of an element corresponds to the number of protons in the nucleus of an atom of that element. Element 111 has one hundred protons, hence "unun1" (un-un-i). This naming convention is used for elements beyond those that have established names.

Once a new element is synthesized and its existence is confirmed, the discoverers are invited to propose a permanent name and symbol. This proposal is then reviewed by IUPAC. If approved, the element is officially added to the periodic table with its permanent designation, and the temporary name is retired. For instance, element 111 was eventually named Roentgenium (Rg) in honor of Wilhelm Conrad Röntgen. Therefore, unun1 is no longer in use as a designation for any known element.