Ununennium

Ununennium is the systematic name given to the chemical element with atomic number 119, meaning that an atom of it has 119 protons. The symbol used is Uue. This element has not yet been synthesized in the laboratory, so all information about it is based on predictions from chemical and nuclear physics principles.

The name 'ununennium' comes from a systematic naming system developed by the International Union of Pure and Applied Chemistry (IUPAC) for as-yet-unknown elements: un (1), un (1), enn (9), followed by the suffix -ium. Once the element is synthesized and confirmed, the team that discovered it has the right to propose a permanent name, which IUPAC must approve.

Position in the periodic table

Element 119 begins a new row of the periodic table, following the seventh row. According to the organization of the periodic table, ununennium is expected to occupy group 1, the alkali metals group, alongside lithium, sodium, and francium. However, calculations accounting for relativistic effects—the influence of light-speed phenomena on electron behavior—suggest that its chemical properties may differ from those of ordinary alkali metals, for example in the energy required to remove an electron.

Synthesis attempts

Synthesizing heavy elements depends on colliding two atomic nuclei using particle accelerators. Research groups from Germany, Russia, and Japan have attempted to create element 119 by combining various target nuclei and projectiles. So far, none of these attempts have produced confirmed results. The challenge is partly that the probability of a successful collision (the cross-section) becomes extremely small as atomic number increases, and the half-life of the resulting nucleus is expected to be very short.

Stability and the 'island of stability'

The 'island of stability' hypothesis suggests that certain combinations of protons and neutrons could yield nuclei with much longer lifespans. Elements above 118 are generally thought to decay rapidly through alpha emission or fission. Therefore, even if synthesized, measuring its chemical properties could prove extremely difficult.