Periodic table: Scientists propose new way of ordering the elements
New proposal
The latest attempt to order elements in this mannerwas recently published in the Journal of Physical Chemistryby scientistsZahed AllahyariandArtem Oganov. Their approach,building on the earlier work of others, is to assign to each element what’s called a Mendeleev Number (MN). There are several ways to derive such numbers, but the latest study uses a combination of two fundamental quantities that can be measured directly: an element’s atomic radius and a property calledelectronegativitywhich describes how strongly an atom attracts electrons to itself.
If one orders the elements by their MN, nearest neighbors have, unsurprisingly, rather similar MNs. But of more use is to take this one step further and construct a two-dimensional grid based on the MN of the constituent elements in so-called “binary compounds.” These are compounds composed of two elements, such as sodium chloride, NaCl.
What is the benefit of this approach? Importantly, it can help to predict the properties of binary compounds that haven’t been made yet. This is useful in the search for new materials that are likely to be needed for both future and existing technologies. In time, no doubt, this will be extended to compounds with more than two elemental components.
A good example of the importance of the search for new materials can be appreciated by considering the periodic table shown in the figure below. This table illustrates not only the relative abundance of the elements (the larger the box for each element, the more of it there is) but also highlights potential supply issues relevant to technologies that have become ubiquitous and essential in our daily lives.
Take mobile phones, for instance. All of the elements used in their manufacture are identified with the phone icon and you can see that several required elements are becoming scarce – their future supply is uncertain. If we are to develop replacement materials that avoid the use of certain elements, the insights gained from ordering elements by their MN may prove valuable in that search.
After 150 years, we can see that periodic tables are not just a vital educational tool, they remain useful for researchers in their quest for essential new materials. But we should not think of new versions as replacements for earlier depictions. Having many tables and lists only serves to deepen our understanding of how elements behave.
This article is republished fromThe ConversationbyNick Norman, Professor of Chemistry,University of Bristolunder a Creative Commons license. Read theoriginal article.
Story byThe Conversation
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