Though in Mendeleev’s day, there was only atomic weight to go by. According to Peter Wothers, director of studies in chemistry at St Catharine’s College in Cambridge, UK, it’s ‘particularly pleasing’ for a chemist to see the elements in a spiral conformation because it keeps their atomic numbers in order, in one long, unbroken string. Following in the footsteps of de Chancourtois, many chemists attempted to perfect the spiral configuration. It was between Mendeleev’s first and final drafts that element-arranging really took off. Source: Manuscript: © Science & Society Picture Library/SSPL/Getty Images Typed version: © Ann Ronan PictureĪs we all know, Dmitri Mendeleev got it right with his periodic table in 1869 He did correct these, but only based on the patterns he saw in their properties. Atomic numbers weren’t discovered until after Mendeleev’s death, though, so his first tables showed some elements in the wrong order based on atomic weights. ‘With atomic number, which is now the ordering principle, those triads are exact,’ says Scerri. As Scerri explains, using atomic weight meant these ‘triads’ weren’t exact, but Döbereiner was still able to place bromine between chlorine and iodine, and sodium between lithium and potassium as early as 1829. In each group of three, the weight of the middle element was approximately the average of the other two. Sadly for de Chancourtois, the need to view his system in 3D and being published in a geology journal meant it never caught on among chemists.Įarlier still, German chemist Johann Döbereiner had grouped the elements into threes, based on their atomic weights. Wrapping it around a cylinder produced vertical lists of similar elements akin to Mendeleev’s groups. De Chancourtois arranged the elements in order of their atomic weights and recognised that certain properties recurred in regular intervals – mirroring the periodicity that Mendeleev displayed in the rows of his table. The graph looked more like a nautical chart than a table of elements, but it had a lot in common with Mendeleev’s version. Even before Mendeleev scribbled his first draft in 1868, the French geologist, Alexandre-Emile Béguyer de Chancourtois, formulated his vis tellurique, or ‘telluric screw’, a graph of the elements with tellurium at its centre that he displayed on a cylinder. But over the last century and a half, it has seen some bizarre and occasionally beautiful reimaginings. Its conception is, of course, attributed to Dmitri Mendeleev, the Russian chemist whose moment of genius 150 years ago we are celebrating with the International Year of the Periodic Table. Constructing a periodic table to satisfy the keen eye of a chemist is an art as much as a science.įrench geologist de Chancourtois’s ‘telluric screw’ was a graph of the elements with tellurium at its centre, displayed on a cylinder. Meanwhile, as a system for organising chemical elements, scientists are still debating the layout. ‘Everything you’d care to mention,’ he says. He notes that its best known configuration – the one we’re familiar with from chemistry textbooks – has been repurposed to classify fruits and vegetables, swear words and even jazz musicians. ‘It’s become a cultural icon,’ says chemical philosopher Eric Scerri of the University of California, Los Angeles in the US, who has written several books about the periodic table. Turning anything into cupcakes makes it more palatable, of course, but the fact that one of these tempting tables, created by a chemical engineering student called Rachel in 2012, has been viewed over half a million times says something about the periodic table and what it symbolises. Your ‘periodic table of cupcakes’ will almost certainly be rewarded by an avalanche of likes, upvotes, reposts or whatever your preferred social currency is. Then there’s the small matter of baking, icing and systematically labelling 118 cupcakes, one for each of the elements. All you need is a kitchen and a copy of the periodic table. It doesn’t take a genius to impress the internet’s science scene.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |