Our modern lifestyles draw heavily on finite resources of elements

An image showing the periodic table elements that are becoming increasingly scarce

Source: © SciComm Studios/Anna Tanczos

Chemists have highlighted a number of elements we risk running out of. There is a serious threat we may lose some of them over the next 100 years. Some elements have limited availability and are increasingly used, including lithium, phosphorus, platinum, nickel, helium and indium. We rely on these elements for getting from place to place, for our health, our food supply, our energy and for communication.

Chemists have highlighted a number of elements we risk running out of. There is a serious threat we may lose some of them over the next 100 years. Some elements have limited availability and are increasingly used[1] , including lithium, phosphorus, platinum, nickel, helium and indium. We rely on these elements for getting from place to place, for our health, our food supply, our energy and for communication.

In your class

Download this article and the teaching resources from rsc.li/2X1xYqs

The International Year of the Periodic Table provides an excellent opportunity to revisit some core ideas about the periodic table. This article presents the elements of the periodic table in the context of sustainability and our use of elements in scientific innovation. Use the resource that goes with the article as a revision lesson for practising long exam question technique.

Metal-powered transport

Oxides of rare metals such as platinum, rhodium and nickel are in short supply since they are used as catalysts in car catalytic converters. These converters oxidise poisonous carbon monoxide to carbon dioxide, reduce noxious oxides of nitrogen to harmless nitrogen and limit air pollution. Luckily, some companies are making less-polluting electric cars that do not need catalytic converters. However, these cars are powered by batteries dependent on lithium. Although ores of lithium are reasonably common in the Earth’s crust, demand for the metal is soaring and putting resources under pressure. So, the search is on for alternative but plentiful metals.

Phosphorus is hardly uncommon and yet there is now a risk to future supply

Scientists have designed a rechargeable battery based on aluminium, the third most abundant element in the Earth’s crust, which could outperform lithium batteries one day. Another recent report indicates magnesium or aluminium could replace lithium. These research efforts are also driven by safety concerns. Lithium batteries are prone to bursting into flames because fingers of conducting lithium residues, called dendrites, form across the battery cell, which short-circuit the device. Magnesium and aluminium are not subject to dendrite growth and could be intrinsically safer.

Scientists have designed a rechargeable battery based on aluminium, the third most abundant element in the Earth’s crust, which could outperform lithium batteries one day[2]. Another recent report indicates magnesium or aluminium could replace lithium[3]. These research efforts are also driven by safety concerns. Lithium batteries are prone to bursting into flames because fingers of conducting lithium residues, called dendrites, form across the battery cell, which short-circuit the device. Magnesium and aluminium are not subject to dendrite growth and could be intrinsically safer.

Fertiliser going to waste

Phosphorus is hardly uncommon and yet, through widespread use as phosphates in crop fertilisers, there is now a risk to future supply. Many reserves of rock phosphate are likely to be exhausted before the end of the century.

Recycling agricultural phosphorus back into fields from agricultural runoff could be one way to prevent this since phosphorus present causes algal blooms in downstream ecosystems. As the algae die, they are decomposed by oxygen-consuming bacteria, which rob other fish and animal life of oxygen. The Swedish government intends to legislate on mandatory phosphorus recovery from sewage sludge, a step already introduced in Germany in 2017, because human urine is rich in the element. In Germany, a pilot study is expected to lead to the first plant for extracting phosphorus from sewage sludge to be opened in 2023. By recycling phosphorus from sewage, they offset the import of rock phosphate and reduce environmental impact on water resources.

Recycling agricultural phosphorus back into fields from agricultural runoff could be one way to prevent this since phosphorus present causes algal blooms in downstream ecosystems. As the algae die, they are decomposed by oxygen-consuming bacteria, which rob other fish and animal life of oxygen. The Swedish government intends to legislate on mandatory phosphorus recovery from sewage sludge, a step already introduced in Germany in 2017, because human urine is rich in the element. In Germany, a pilot study is expected to lead to the first plant for extracting phosphorus from sewage sludge to be opened in 2023, as reported by Aquatech (bit.ly/2SgqYrk). By recycling phosphorus from sewage, they offset the import of rock phosphate and reduce environmental impact on water resources.

Helium health

Helium is the light gas familiar to us as a safe filling for party balloons. Helium readily escapes through balloon membranes. The atoms are so light they will also escape into space from the Earth’s atmosphere.

Magnetic resonance imaging (MRI) equipment is non-invasive way of diagnosing medical conditions through detailed pictures of internal structures in the body. MRI depends on a powerful magnet which is cooled by liquid helium to extremely low temperatures (helium is a liquid at or below 269K at normal atmospheric pressure) to produce conditions for superconductivity. Another application of the technique is nuclear magnetic resonance (NMR) which is used in chemistry to provide details of molecular structure.

Helium is trapped in small quantities in petroleum and is a by-product of refining. New oil fields continue to be found and old ones exploited, but sources of the gas are very restricted, and cannot be replaced if depleted. Helium supply needs to be carefully conserved because there are no good alternatives for its uses. Other light gases, such as hydrogen, are not safe to use.

Endangered elements of the periodic table

Practice extended exam questions, ages 14–16

Older chemistry students who are approaching their exams need to be able to comprehend paragraphs of text. Students need to organise the information they give to answer questions worth a higher number of marks (6—8). In the attached revision activities, students use the article to develop skills in selecting, organising and presenting information to answer a given question.

Download the practice extended exam questions (as a pdf or MS PowerPoint) and the teacher notes (as a pdf or MS Word).

Element-eating electronics

Indium is a rare metal used in television, computer and mobile phone flat-panel display screens. It is in solar cells, which convert light into electricity – a renewable, environmentally-friendly method of power generation. Indium is also used to dope silicon in microchip production.

At the current rate of indium consumption, which is accelerating world-wide, supplies of indium ore could dwindle to nothing over the next 50 years. The problem must be addressed by recycling indium already in use and finding alternative conductors made from more abundant materials. One example alternative is indium zinc oxide, which involves reduced indium content. Conducting polymers, such as graphene and polyaniline, which could reduce indium in silicon chips, are another.

At the current rate of indium consumption, which is accelerating world-wide, supplies of indium ore could dwindle to nothing over the next 50 years. The problem must be addressed by recycling indium already in use and finding alternative conductors made from more abundant materials. One example alternative is indium zinc oxide, which involves reduced indium content. Conducting polymers, such as graphene and polyaniline, which could reduce indium in silicon chips, are another[4].[5]

For 150 years chemists have striven to identify ‘missing’ elements in the periodic table. How ironic that some elements’ existence should now be threatened today by human wastefulness. We must identify ways to recycle elements by designing products based on a life-cycle of extraction, production, consumption and re-use. This way, we may be able to protect the endangered elements.

References

[1]A sustainable global society, Chemical Sciences and Society white paper, 2011

[2]D J Kim et al, Nat. Energy, 2019, 4, 51, DOI: 10.1038/s41560-018-0291-0

[3]M Jackle et al, Energy Environ. Sci., 2018, 11, 3400, DOI: 10.1039/c8ee01448e

[4]C O Baker et al, Chem. Soc. Rev., 2017,46, 1510, DOI: 10.1039/C6CS00555A

[5]P Chandrasekhar, Conducting Polymers, Fundamentals and Applications, 2nd Edition Springer March 2018

A starter activity to introduce students to the common elements found in the Earth’s crust

Resources developed in partnership with BOC introducing how we get useful gases from the air. Includes a video, teacher notes and student handouts

A series of short, fun videos exploring the chemistry of the alkali metals, taken from a lecture by Dr Peter Wothers at the University of Cambridge

Part of the Learning About Materials resources collection, this resource gives a broad picture of how platinum – and other associated rare metals – are mined and refined.

Scientific reading teacher development materials and student sheets (held in STEMnet eLibrary, free registration required)

A starter activity to introduce students to the common elements found in the Earth’s crust: rsc.li/2TJbE2M

Resources developed in partnership with BOC introducing how we get useful gases from the air. Includes a video, teacher notes and student handouts: rsc.li/2MU4Ehh

A series of short, fun videos exploring the chemistry of the alkali metals, taken from a lecture by Peter Wothers at the University of Cambridge: rsc.li/2SxZGM9

Part of the Learning About Materials resources collection, this resource gives a broad picture of how platinum – and other associated rare metals – are mined and refined: rsc.li/2RLB8Ll

Scientific reading teacher development materials and student sheets (held in STEMnet eLibrary, free registration required):

  • bit.ly/2GiiBVE
  • bit.ly/2SuP2WJ