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.

The groups credited for creating them – in Japan, Russia and the US – have spent several years gathering enough evidence to convince experts from Iupac and its physics equivalent, the International Union of Pure and Applied Physics, of the elements’ existence. 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.

Confirmation of four new elements completes seventh row of periodic table from the Royal Society of Chemistry by Emma Stoye.