Rare earth metals are a relatively small group of elements, which has a total of 17 representatives. All of them are represented by silver-white substances.
Rare earth elements and the history of their discovery
This group of substances was discovered relatively recently. The samples were first discovered in 1794. At that time, a chemist from Finland, Juhan Gadolin, studied ore samples near a place called Itterby. Here he discovered an unknown "liquid earth", which he then named after his location - yttrium. After some time, the obtained samples were once again examined by Martin Klaport, who isolated an additional substance called cerium in honor of the planet Ceres .
And by 1907, 14 such elements had already been discovered.
The very name “rare earth metals” was introduced at the end of the 18th century. Here, the fact that all the elements of this group form refractory oxides, which practically do not dissolve in water, played a role. In addition, scientists of that time mistakenly believed that these metals are rarely found in the earth's crust.
Rare earth metals: representatives of the group
As already mentioned, this group has 17 chemical elements. These include:
- Lanthanum.
- Cerium (named after the planet Ceres).
- Neodymium.
- Pradeozyme.
- Samarium.
- Promethium.
- Gadolinium.
- Europium.
- Terbium.
- Holmium.
- Dysprosium.
- Erbium.
- Ytterbium.
- Lutetium.
- Thulium.
Interestingly, the external electronic levels of these atoms are almost the same. It is with this that the chemical and physical properties of metals are associated.
Rare earth metals and their chemical properties
Representatives of this group have a fairly high reactivity, which is especially high when heated. For example, at elevated temperatures, some metals are able to react with hydrogen.
In addition, when heated, these elements interact with oxygen to form stable, water-insoluble oxides. By the way, during the combustion of metals in atmospheric oxygen, a significant amount of heat is released. It is for this group that pyrophorism is characteristic - the property of sparking in the air.
Rare earth metals can also form hydroxides, which are poorly soluble in water and have some amphoteric properties.
Almost all representatives of the group are characterized by an oxidation state of +3. The activity of the elements is not the same. The most active is lanthanum.
Rare earth mining
In most cases, rare earth metals are found together. In one breed sample, several representatives of the group are contained at once. To date, more than 250 minerals are known, which contain rare-earth elements. The main minerals include monazite, xenim parisite, orthite.
The most common substance in the earth's crust is cerium. But thulium and lutetium in nature contains the least amount.
In 2008, around 124 thousand tons of rare earth metals were mined worldwide. The leaders in this production were considered countries such as India, China and Brazil.
Another place of extensive rare earth deposits was discovered in 2011. These territories are located on the bottom of the Pacific Ocean, not far from the Hawaiian Islands, French Polynesia and Tahiti.
Rare earth metals and their use
These elements are used in completely different industries. For example, they are widely used in the glass industry. Firstly, they increase the transparency of the glass. Secondly, these metals are used to produce glass for special purposes - glass that absorbs ultraviolet rays or transmits infrared cures. With the help of rare earths, heat-resistant glass is produced.
In oil refining, these elements act as catalysts. They are also used in the chemical industry for the production of high-quality paints, varnishes and pigments.