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Periodic table: new version warns of elements that are endan

来源:未知 |最近更新: 2019-04-16

It is amazing to think that everything around us is made up from just 90 building blocks – the naturally occurring chemical elements. Dmitri Mendeleev put the 63 of these known at the time into order and published his first version of what we now recognise as the periodic table in 1869. In that year, the American civil war was just over, Germany was about to be unified, Tolstoy published War and Peace, and the Suez Canal was opened.

There are now 118 known elements but only 90 that occur in nature. The rest are mostly super-heavy substances that have been created in laboratories in recent decades through nuclear reactions, and rapidly decay into one or more of the natural elements.

Where each of these natural elements sits in the periodic table allows us to know immediately a great deal about how it will behave. To commemorate the 150th anniversary of this amazing resource, UNESCO has proclaimed 2019 as the International Year of the Periodic Table.

As part of the celebrations, the European Chemical Society has published a completely new version of the periodic table – see main image. It is designed to give an eye-catching message about sustainable development; based on an original idea in the 1970s from the American chemist William Sheehan, the table has been completely redrawn so that the area occupied by each element represents its abundance on a log scale.

Red for danger

Each area of the new table has been colour coded to indicate its vulnerability. In most cases, elements are not lost but, as we use them, they become dissipated and much less easy to recover. Red indicates that dissipation will make the elements much less readily available in 100 years or less – that’s helium (He), silver (Ag), tellurium (Te), gallium (Ga), germanium (Ge), strontium (Sr), yttrium (Y), zinc (Zn), indium (In), arsenic (As), hafnium (Hf) and tantalum (Ta).

Read more: We'll all be worse off when the helium balloon pops

To give just a couple of examples, helium is used to cool the magnets in MRI scanners and to dilute oxygen for deep sea diving. Vital rods in nuclear reactors use hafnium. Strontium salts are added to fireworks and flares to produce vivid red colours. Yttrium is a component of camera lenses to make them shock and heat resistant. It is also used in lasers and alloys. Gallium, meanwhile, is used to make very high-quality mirrors, light-emitting diodes and solar cells.