Explanation. The number associated with an element refers to the number of protons that make up its nucleus. For example, a hydrogen atom (element number 1) is made up of a single proton while an uranium atom (element number 92) has 92 protons. This makes uranium the heaviest natural element known.
But over the years, elements heavier than uranium have been created in the laboratory. The four most recent are numbered 113, 115, 117 and 118 (the oganesson). Identified in the 2000s and 2010s, they were officially added to the periodic table in 2016 by the International Union of Chemistry.
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The problem is that to get them, we must fuse lighter atoms in particle accelerators…and be very patient: most often, these atoms repel each other and in the very rare cases where it worked, their lifespan was measured in thousandths of a second. This is why they are said to be “unstable”.
However, a theoretical model is that by reaching the number 120, we would touch what physicists call an “island of stability”: elements whose lifespan would no longer be measured in fractions of a second, but in years, or even in millions of years. According to this theory, a “ magic number » of protons and neutrons would ensure this stability.
We are not there yet, but in two pieces of research published separately in recent months, two teams announce having succeeded in synthesizing, in the accelerator of the Lawrence Berkeley Laboratory, in California, element 116 (livermorium). This is not unprecedented, but they would have achieved it with a different method from their predecessors. Method which, they say, would open the door to the creation of heavier elements, including the mythical element 120. The first teamfrom Lund University, Sweden, has so far only produced a pre-published study in July, while the secondfrom Berkeley University, has just published its results in the magazine Physical Review Letters.
Whichever method proves most promising, it may be years before a group demonstrates the ability to produce an “element 120,” assuming it succeeds. But if someone succeeds, it will mean that there is something fundamental to nuclear physics which still eluded us: how many protons and neutrons can coexist within an atom – for example, what are the limits of what can be forged within the stars, in the four corners of the cosmos? What’s more, if such an atom was indeed “stable”, the researchers could thanks to it better understand the fundamental bases of matter —at least that’s what they hope.
