editorial ’s table of contents The United Nations has declared 2019 to be the International Year of the to coincide with this iconic chemical chart turning 150 years old. We join in with the celebrations by publishing a collection of articles that explore the edges of the periodic system and look at some of the elements that do — and don’t — make up the table.

he periodic table catalogues all of the now means ‘synthesizing’ it. As Hiromitsu known atomic building blocks, neatly Haba explains in a Comment article, this Torganized in a system that reflects their involves some serious calculations and heavy structures, characteristics and reactivities — instrumentation, as well as a good deal of yet it is far more than a cleverly arranged list. patience. One needs to bombard target nuclei As chemistry has progressed, scientists have with projectile nuclei — accelerated at just the brought new elements to the table, gained right speed for them to be able to fuse — and a better understanding of their properties hope to be able to detect a few fleeting fused and classified them into a chart, the shape of nuclei through their decay pattern. which has evolved accordingly. Over time, the In this month’s In Your Element essay, table has become a widely recognized symbol element-hunter Yuri Oganessian recounts of the field, and understanding its evolution Early version of Mendeleev's table. Credit: ITAR- such a superheavy synthesis — that of reveals much about the history and culture TASS News Agency / Alamy Stock Photo the ‘doubly odd’ , whose odd of chemistry. number of protons and of neutrons confer Chemists noticed early on that some it greater stability than its even-numbered elements displayed similar properties and The International Year of the Periodic counterparts. Oganessian is one of only two attempted to classify them on this basis. By Table of Chemical Elements (IYPT; https:// scientists to have had an element named 1789, Antoine Lavoisier had compiled a list www.iypt2019.org/) provides chemists with after them in their lifetime, the other being of 33 ‘elements’ — or substances that could a platform to promote the fundamental Glenn Seaborg. With its 118 protons, his not be broken down further — divided into importance of the periodic table, the elements eponymous element is the gases (which included light and caloric, the and their applications in modern society — heaviest element yet made on Earth. ‘substance’ of heat), metals, non-metals and particularly the key role that chemistry can, But what is the heaviest element that earths (‘salifiable simple earthy substances’ and must, play in addressing many of the is naturally formed, ask Brett Thornton such as chalk and clay). By 1829, Johann world’s critical challenges, such as ensuring and Shawn Burdette in a Comment article Wolfgang Döbereiner had grouped together food and water security, better health and — and can we detect it? The answer is far several sets (‘triads’) of three elements and achieving a sustainable future. The IYPT may from straightforward, courtesy of the many observed linear relationships in some of also prompt chemists to take a closer look transuranium isotopes that decay into one their properties (such as atomic weight or at some of the elements that make up the another at different rates, fleetingly appear density). In the middle of the 19th century, periodic table — as well as some that don’t. in ores and even fall from the sky. Of around sixty elements were known. A collection of articles in this issue reconciles course, elements that fall from the sky have In the 1860s, Julius Lothar Meyer and elements old and new, natural and synthetic, captured the imagination of many through independently developed established and discredited. their appearances in fiction. Vibranium for similar systems to classify these elements The gaps in the early version of the example, which makes up Black Panther’s and were both awarded the Royal Society’s periodic table inspired chemists and non- suit, is mined from a meteorite. In a Davy Medal in 1882 ‘for their discovery chemists alike to imagine and/or search for Comment article, Suze Kundu considers of the periodic relations of the atomic new elements — though more often than this and other elements of fantasy — and weights’. John Newlands proposed a related not claims of a discovery lacked rock-solid discusses their perhaps surprisingly close classification in 1866 that followed a ‘law of evidence. In a Comment article, Michelle relationship to real-life materials. octaves’, but it did not gain much traction at Francl ponders on those elements that never The periodic table is an icon — one that the time. Recognition came later, however, were. Although their existence was mere contains within it the code for all atomic and in 1887 he was also awarded the Davy wishful thinking, some of these phantoms building blocks that we know of. As such, Medal ‘for his discovery of the periodic law that didn’t stand up to scrutiny linger on, it underpins the field of chemistry and any of the chemical elements’. Nevertheless, it particularly through their names. Once a other scientific discipline that relies on it, such is Mendeleev (who published his chart in name has been suggested (but not ultimately as materials science, nanotechnology and 1869) that is nowadays widely credited for adopted) for an element it cannot be reused, biology to name but a few. The periodic table devising the original version of the modern and Francl muses on whether ill-intentioned offers fact and inspires fiction. It should be periodic table. Meyer’s was published just scientists could use this to hinder a nemesis’s celebrated and the articles mentioned above one year later, although a preliminary chance to ever have an eponymous element! do just that; they are gathered together in an version appeared in an 1864 textbook; To have the honour of naming an online collection, to which further pieces will the clinching factor, however, may be that element, one first needs to discover it — and also be added throughout the IYPT — so Mendeleev not only included all known this is easier said than done. The days of please do check back periodically. ❐ elements, but also used the gaps in his painstakingly searching through ores for a table to (correctly) predict the properties of substance that may or may not be there are Published online: 14 December 2018 elements that were yet to be discovered. long gone, and ‘discovering’ a new element https://doi.org/10.1038/s41557-018-0199-0

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