GENERAL ARTICLE Endangered Elements of the Periodic Table Dhrubajyoti Chattopadhyay Recent studies show that nearly 40% of the 118 elements that make up everything – from the chemist’s arsenal to a variety of consumer products, are facing depleting supplies. Based on this data, in 2011, Mike Pitts and his colleagues at the Chemistry Innovation Knowledge Transfer Network devel- oped a new type of periodic table. Their analysis revealed that 44 elements are facing limited supply, or are under the threat of becoming scarce or inaccessible. These includes all Dhrubajyoti Chattopadhyay of the rare earth elements, as well as zinc, gallium, germa- is working as Education ffi nium, helium, silver, and even phosphorus. The Royal So- O cer in the North Bengal Science Centre under the ciety of Chemistry has also published a color-coded periodic National Council of Science table, indicating the ‘endangered elements’. The objective of Museums. He is mainly this article is to draw attention to this issue, and create aware- engaged in popularization of ness about the scientific, social and economic impacts of this science and works towards inculcation of scientific problem. temper among the students In March 1869, Dmitri Mendeleev proposed his periodic law and and public. He has many popular science articles to his 1 presented his famous periodic table . The idea, however, was credit. not accepted warmly by the scientists of that time. The famous chemist, Robert Bunsen even made a caustic remark, saying – “One can draw any number of such generalizations on the ba- sis of figures printed in stock-exchange bulletins.” The periodic 1See S Vatsala, There is much table has been like a compass to the chemists seeking new ele- more to Mendeleevs periodic ments in the boundless sea of chemistry. It also helped them dis- table than meets the eye, Reso- nance, Vol.3, No.11, pp.75–81, cover nearly a dozen new elements, earlier predicted by Dmitri 1998. Mendeleev. With the progress of science, the periodic table has undergone many transformations and incorporation of new ideas. The modern version of the periodic table (Figure 1) was created by Nobel Laureate Glenn Seaborg during 5th decade of 20th cen- tury. It is elegant in its simplicity, yet powerful in its ability to enlighten us. Keywords Periodic table, endangered ele- The chemical elements which compose the Earth are finite. These ments, minerals, ores. RESONANCE | January 2017 79 GENERAL ARTICLE Figure 1. Glenn Seaborg’s periodic table. To maintain a steady elements are also essential to fuel all human needs. But presently, supply of essential we are mining and redistributing these fundamental elements at elements, there is an such a rapid rate that many are already in short supply and will urgent need to reframe our present be completely exhausted within next few decades. To maintain a understanding of mining steady supply of these essential elements, there is an urgent need and consumption, along to reframe our present understanding of mining and consumption, with environment and along with environment and waste management. Aiming towards waste management. this, in 2011, Mike Pitts and his colleagues at the Chemistry Inno- vation Knowledge Transfer Network, UK, developed a new type of periodic table. The objective of this newly devised periodic ta- ble (Figure 2) was to show the availability and distribution of the elements in nature and to indicate which elements are at risk and may become scarce. Their analysis revealed 44 elements which are facing limited supply, or are under the threat of becoming scarce or inaccessible. The list includes all of the rare earth el- ements, as well as zinc, gallium, germanium, helium, silver, and In 2011, Mike Pitts and even phosphorus. The situation is so critical that the Royal Soci- his colleagues at the ety of Chemistry has published a color-coded periodic table that Chemistry Innovation indicates the extent to which these elements – the basic building Knowledge Transfer Network, UK, developed blocks of nature, are now becoming ‘endangered’. The impact of a new type of periodic this periodic table is striking. The periodic table acts as a cata- table to show the lyst for geopolitical relations and is influencing the consumption availability and patterns of most of the countries having these resources. distribution of the elements in nature and to But Mike Pitts and his colleagues were not the first ones to have indicate which elements conducted this kind of a study. About 20 years back, a simi- are at risk and may become scarce. lar study was conducted at Kyoto University for few metals like 80 RESONANCE | January 2017 GENERAL ARTICLE Figure 2. Endangered elements (Source: Chem- istry Innovation Knowledge Transfer Network). Ag, Pb, Hg, Au, Zn, Cu, etc. The research clearly indicated the concern surrounding this issue. Based on the data collected, the investigators at Kyoto University published a report which indi- cated that 80% of the world’s mercury (Z = 80), 75% of its silver (Z = 47), tin (Z = 50), and lead (Z = 82), 70% of gold (Z = 79) and zinc (Z = 30), and 50% of copper (Z = 29) and manganese (Z = 25), had at the time, already been processed to meet human re- quirements. Hence it is quite apparent that some of the naturally occurring elements have been under serious threat since a long time. Before discussing this periodic table, it is also worth noting what Mike Pitts and his colleagues actually mean, when they call an element endangered. It does not imply that the element will dis- ‘Endangered’ does not appear from the Earth completely. It means that there will come a imply that the element point when the supply of these elements will be limited or when will disappear from the Earth completely. It it no longer remains economically viable to extract or use these means that there will elements. At such a juncture, we will have to seek alternatives. come a point when the The situation is attributed to the increasing use of these elements. supply of these elements With the progress in technologies, the use of these materials have will be limited or when it no longer remains increased many fold within the last two decades. As a result, economically viable to these elements are rapidly converted into commodities from the extract or use these ore. Let us now discuss the eight elements which are under seri- elements. ous threat. RESONANCE | January 2017 81 GENERAL ARTICLE Endangered Gaseous Element: Helium In 2013, Qatar started Helium, being the second most abundant element in the universe, the world’s largest helium unit known as the might seem to be an odd element in the list of endangered ele- ‘Helium 2 Plant’. ments. This light gas is used in wide range of applications includ- ing helium-filled balloons, and cooling magnets to very low tem- peratures in MRI machines. Presently USA controls the world’s largest supply of helium. But based on the current rates of use, it is estimated that the stocks will meet the demands only a few more years (25 ± 5). While before 2011, despite the future like- lihood of scarcity of helium, it was sold at comparatively lower prices, after the publication of the table, the market price of he- lium has undergone a hike. Not only that, a keen competition has started between the countries to stock helium. In 2013, Qatar started the world’s largest helium unit known as the ‘Helium 2 Plant’. The year 2014 was widely acknowledged as a year of oversupply in the helium business following years of shortage. The issue however, is not the excess use of helium, but that the gas being lighter than air can easily escape the Earth’s atmosphere. This means that the amount of helium on the planet is constantly being depleted. Endangered Elements Mostly Used in Electronics Indium Nowadays most of us are familiar with touchscreen phones or tablets. These devices contain indium, in the form of indium tin oxide. The use of this particular element was not known till a decade ago. Indium tin oxide is a vital component of the touch- screens, used to make a transparent film that conducts electricity. In fact, 45% of all indium extracted has a use involving indium The challenge with tin oxide. indium is that it does not occur in high enough The challenge with indium is that it does not occur in high enough concentrations in ores to concentrations in ores to be profitably extracted. Less than 10 be profitably extracted. indium minerals are known, including dzhalindite (In(OH)3) and indite (FeIn2S4), but none of these are abundant. The bulk of 82 RESONANCE | January 2017 GENERAL ARTICLE indium is obtained as a byproduct during the extraction of zinc, Since 1960’s gallium though it also occur in low concentrations in lead and tin ores. arsenide-based optoelectronic devices, The amount of indium used in a single device like a phone is ac- including light-emitting tually very small – around hundred milligrams or less. Hence, diodes (LEDs), laser recovery of indium from unwanted devices is not very cost effec- diodes, and solar cells have been marketed tive. So scientists are thinking of alternatives to indium. While throughout the world. graphene has seen limited use for this purpose in a small number of smartphones, it remains to be seen whether this will be widely adopted or not. Gallium Currently, gallium is an extensively used element in electron- ics. Gallium is mainly used as gallium arsenide in microwave circuits and high-speed switching circuits. Since 1960’s gallium arsenide-based optoelectronic devices, including light-emitting diodes 2(LEDs), laser diodes, and solar cells have been marketed 2See Kailash Rustogi, What throughout the world.