Critical Elements at a glance

Dmitri Mendeleev published his first periodic table of the elements in 1869 and the modern version adorns the walls of probably every chemistry laboratory in the world.

It has been presented in various guises but no better than the one published last year by the European Chemical Society and I thank my old friend and CSM colleague Richard Edwards for making me aware of this. It is a wonderful way of seeing at a glance that the elements are from finite resources and there is not an inexhaustible supply. Protecting endangered elements needs to be achieved on a number of levels. As individuals, we need to question whether upgrades to our phones and other electronic devices are truly necessary, and we need to make sure that we recycle correctly to avoid old electronics ending up in landfill sites or polluting the environment. 

In a recent posting I questioned the promises of politicians such as Boris Johnson who make overly optimistic demands on the progress towards a "green revolution" and the European Chemical Society hopes that this unique and thought-provoking Periodic Table will lead to reflection and ultimately action.

The area allotted to each element in the table reflects its abundance on earth, and is colour-coded according to its likely future availability. The elements used in smart phones are also identified, which is of particular importance as a smartphone uses around 30 of these elements, many of which, due to increasing scarcity, may be of great concern in future, particularly with the need to mine more and more of these elements to satisfy the 4th Industrial Revolution. Around 10 million smartphones are discarded or replaced every month in the European Union alone, so we need to carefully look at our tendencies to waste and improperly recycle such items. 

Good examples are elements such as gallium and indium which are essential in smart phones. Gallium nitride is a semi-conductor, and without indium, alloyed with tin (also in limited supply) we would not have touch screens. They are used in tiny quantities in each smart phone, but as around 2 billion phones are manufactured each year the supply is becoming critical.

There are no indium or gallium mines, however. These metals are the byproducts of refining base metals, particularly zinc ores, and as can be seen in the table, zinc is also under increasing threat due to increased use, mainly for galvanising other metals such as iron. Metals vital to the new industrial revolution, such as copper, lithium and neodymium are all shaded yellow, showing a future risk to supply.

It is worth looking at two elements whose supply is rarely questioned, the two most abundant elements in the Universe, hydrogen and helium.  Hydrogen is the primordial atom, the fuel for the stars, the primary product of fusion being helium.

Hydrogen is in great abundance on earth, but does not occur naturally, being present in a multitude of molecules, the most common being water. It is a potential competitor to the electric vehicle, petrol and air being replaced in the internal combustion engine by the combustion of hydrogen, and oxygen from the air, to produce a harmless exhaust of water vapour.

Hydrogen is not cheap to produce and store, however. The majority of hydrogen (~95%) is currently produced from fossil fuels by steam reforming of natural gas, partial oxidation of methane, and coal gasification. Other methods include the energy intensive electrolysis of water, the opposite of what occurs in the hydrogen fuel cell.

Although helium is the second most abundant element in the universe, it is very rare on earth, being mostly created by the natural radioactive decay of heavy radioactive elements such as thorium and uranium. It is trapped with natural gas from which it is extracted commercially by low-temperature fractional distillation. Helium is an important constituent in deep diving gas mixtures, replacing nitrogen, which causes narcosis and 'the bends' when compressed air is breathed at depth. It has the lowest boiling point of any element, at -269C, just a few degrees above absolute zero (-273C). This makes it of key importance for superconducting magnets used in MRI scanners and other applications, which must be supercooled to generate the hugely powerful magnetic fields required.

Although helium is a critical element, some of it is wasted, as it is used to fill party and wedding balloons. Once the balloons are released they rise and eventually burst, but of course the helium does not sink to earth, it rises and is lost in space.  Although the amount that is used in party balloons is fairly small compared to its other main uses, it provides an example of the trivial use of something we should be valuing a little bit more.

This version of the Periodic Table should, I feel, be on the walls of every scientist and politician. It provides a constant reminder of how much we should value and conserve our natural resources, and how true it is that everything we use is either mined or grown.

@barrywills