Confirmation that four new elements – those with atomic numbers 113, 115, 117 and 118 – have indeed been synthesised has come from the International Union of Pure and Applied Chemistry (Iupac), completing the seventh row of the periodic table.

All four are highly unstable superheavy metals that exist for only a fraction of a second. They are made by bombarding heavy metal targets with beams of ions, and can usually only be detected by measuring the radiation and other nuclides produced as they decay.

Element 113 – currently known by its placeholder name ununtrium – is the first to be discovered in east Asia. It was created by Kosuke Morita’s group at the RIKEN Nishina Center for Accelerator-based Science in Japan, by firing a beam of zinc-70 at a target made of bismuth-209. The group first claimed to have created the element in 2004, but there was still some uncertainty at that time because of the instability of one of its decay products. They followed up these experiments with more convincing evidence in 2012.

Elements 115 (ununpentium) and 117 (ununseptium) were discovered by groups collaborating across three institutions – Lawrence Livermore National Laboratory in the US, the Joint Institute for Nuclear Research collaboration is also credited with having fulfilled the criteria for discovering element 118 (ununoctium) in work published in 2006.

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