The lithium It is a metallic element whose chemical symbol is Li and its atomic number is 3. It is the third element in the periodic table and heads group 1 of the alkali metals. Of all metals, it is the one with the lowest density and highest specific heat. It is so light that it can float on water.
Its name derives from the Greek word 'lithos' which means stone. They gave it this name because it was discovered precisely as part of some minerals in igneous rocks. In addition, it showed characteristic properties similar to those of the metals sodium and calcium, which were found in vegetable ashes..
It has a single valence electron, losing it to become the Li cation+ in most of your reactions; or sharing it in a covalent bond with carbon, Li-C in organolithium compounds (such as alkyl lithiums).
Its appearance, like many other metals, is that of a silvery solid that can turn grayish if exposed to moisture. It can show blackish layers (upper image), when it reacts with the nitrogen in the air to form a nitride.
Chemically it is identical to its congeners (Na, K, Rb, Cs, Fr), but less reactive since its single electron experiences a much greater force of attraction due to being closer to it, as well as due to the poor shielding effect of its two internal electrons. In turn, it reacts like magnesium does due to the diagonal effect.
Lithium salts can be identified in the laboratory by heating them in a lighter; the appearance of an intense crimson flame will certify its presence. In fact, it is often used in teaching laboratories for analytical runs..
Its applications vary from being used as an additive for ceramics, glasses, alloys or foundry mixtures, to as a cooling medium and design of highly efficient and small batteries; although explosive, given the reactive character of lithium. It is the metal with the greatest tendency to oxidize and, therefore, the one that gives up its electron the most easily.
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The first appearance of lithium in the universe dates back far, a few minutes after the Big Bang, when the nuclei of hydrogen and helium merged. However, earthly it took time for humanity to identify it as a chemical element.
It was in 1800, when the Brazilian scientist José Bonifácio de Andrada e Silva discovered the minerals spodumene and petalite on the Swedish island of Utö. With this, he had found the first official sources of lithium, but still nothing was known about him.
In 1817, the Swedish chemist Johan August Arfwedson was able to isolate from these two minerals a sulfate salt that contained an element other than calcium or sodium. By then August Johan was working in the laboratories of the famous Swedish chemist Jöns Jacob Berzelius.
It was Berzelius who called this new element, a product of his observations and experiments, 'lithos', which means stone in Greek. Thus, lithium could finally be recognized as a new element, but it still lacked to be able to isolate it..
Just a year later, in 1821, William Thomas Brande and Sir Humphry Davy succeeded in isolating lithium as a metal by applying electrolysis to lithium oxide. Although in very small quantities, they were sufficient to observe its reactivity.
In 1854, Robert Wilhelm Bunsen and Augustus Matthiessen were able to produce lithium metal in larger quantities from the electrolysis of lithium chloride. From here, its production and trade had begun, and demand would grow as new technological applications were found as a result of its unique properties..
The crystalline structure of metallic lithium is body-centered cubic (body centered cubic, bcc). Of all the compact cubic structures, this is the least dense and is consistent with its characteristic as the lightest and least dense metal of all..
In it, the Li atoms are surrounded by eight neighbors; that is, the Li is in the center of the cube, with four Li at the top and bottom at the corners. This bcc phase is also called α-Li (although apparently this name is not very widespread).
Like the vast majority of solid metals or compounds, they can undergo phase transitions when they experience changes in temperature or pressure; as long as they are not founded. Thus, lithium crystallizes with a rhombohedral structure at very low temperatures (4.2 K). Li atoms are almost frozen and vibrate less in their positions.
When the pressure is increased, it acquires more compact hexagonal structures; and when increasing even more, lithium undergoes other transitions that have not been fully characterized by X-ray diffraction.
Therefore, the properties of this “compressed lithium” are still under study. Likewise, it is not yet understood how its three electrons, one of which is valence, intervene in its behavior as a semiconductor or metal at these high pressure conditions..
It seems curious that lithium at this point remains an "opaque book" for those engaged in crystallographic analysis..
This is because, although the electron configuration is 2s1, with so few electrons it can hardly interact with the radiation applied to elucidate its metallic crystals.
Furthermore, it is theorized that the 1s and 2s orbitals overlap at high pressures. That is, both the internal electrons (1stwo) as those of valencia (2s1) govern the electronic and optical properties of lithium in these super compact phases.
Having said that the electron configuration of lithium is 2s1, it can lose a single electron; the other two, from the 1s inner orbitaltwo, would require a lot of energy to remove.
Therefore, lithium participates in almost all its compounds (inorganic or organic) with an oxidation number of +1. This means that in its bonds, Li-E, where E comes to be any element, the existence of the Li cation is assumed+ (be it ionic or covalent actually said bond).
The oxidation number -1 is unlikely for lithium, since it would have to bind to an element much less electronegative than it; fact that in itself is difficult as this metal is very electropositive.
This negative oxidation number would represent a 2s electron configurationtwo (to gain an electron), and it would also be isoelectronic to beryllium. Now the existence of the Li anion would be assumed-, and its derived salts would be called lituros.
Due to its great oxidation potential, its compounds mainly contain the Li cation.+, which, because it is so small, can exert a polarizing effect on bulky anions to form Li-E covalent bonds.
Silvery-white metal with a smooth texture, whose surface turns grayish when oxidized or darkens when it reacts directly with nitrogen in the air to form its corresponding nitride. It is so light that it floats in water or oil.
It is so smooth that it can even be sliced using a knife, or even with fingernails, which would not be recommended at all..
6.941 g / mol.
180.50 ° C.
1330 ° C.
0.534 g / mL at 25 ° C.
Yes, it floats in water, but it immediately begins to react with it. It is soluble in ammonia, where when it dissolves its electrons are solvated to produce blue colors.
0.818 mm Hg at 727 ° C; that is, not even at high temperatures its atoms can barely escape into the gas phase.
0.98 on the Pauling scale.
First: 520.2 kJ / mol
Second: 7298.1 kJ / mol
Third: 11815 kJ / mol
These values correspond to the energies necessary to obtain the gaseous ions Li+, Litwo+ and Li3+, respectively.
179 ° C.
398 mN / m at its melting point.
In liquid state it is less viscous than water.
3.00 kJ / mol.
136 kJ / mol.
24,860 J / mol · K. This value is extraordinarily high; the highest of all elements.
0.6
In nature, lithium occurs in the form of two isotopes: 6Li and 7Li. The atomic mass 6,941 u alone indicates which of the two is the most abundant: the 7Li. The latter makes up about 92.4% of all lithium atoms; Meanwhile he 6Li, about 7.6% of them.
In living beings the organism prefers to 7Li that the 6Li; however, in mineralogical matrices the isotope 6Li is better received and, therefore, his percentage of abundance increases above 7.6%.
Although it is less reactive than the other alkali metals, it is still a fairly active metal, so it cannot be exposed to the atmosphere without undergoing oxidation. Depending on the conditions (temperature and pressure), it reacts with all gaseous elements: hydrogen, chlorine, oxygen, nitrogen; and with solids like phosphorus and sulfur.
There are no other names for lithium metal. Regarding its compounds, a large part of them are named according to the systematic, traditional or stock nomenclatures. Its oxidation state of +1 is practically unchanged, so in the stock nomenclature the (I) is not written at the end of the name.
For example, consider the compounds LitwoO and Li3N.
The LitwoOr it receives the following names:
- Lithium oxide, according to the stock nomenclature
- Lithic oxide, according to traditional nomenclature
- Dilithium monoxide, according to the systematic nomenclature
While the Li3N is called:
- Lithium nitride, stock nomenclature
- Lithic nitride, traditional nomenclature
- Trilithium mononitride, systematic nomenclature
The extent to which lithium may or may not be essential to organisms is unknown. Likewise, the mechanisms by which it could be metabolized are uncertain and it is still being studied..
Therefore, it is not known what positive effects a diet “rich” in lithium can have; even though it can be found in all tissues of the body; especially in the kidneys.
The pharmacological effect of certain lithium salts on the body is known, especially on the brain or nervous system. For example, it regulates the levels of serotonin, a molecule responsible for the chemical aspects of happiness. That said, it is not uncommon to think that it alters or modifies the moods of the patients who consume them..
However, they advise against consuming lithium together with medications that fight depression, as there is a risk of raising serotonin too much.
It not only helps fight depression, but also bipolar and schizophrenic disorders, as well as other possible neurological disorders.
By way of speculation, it is suspected that individuals with diets poor in lithium are more prone to depression or to commit suicide or homicide. However, formally the effects of its deficiency remain unknown..
Lithium cannot be found in the earth's crust, much less in the seas or the atmosphere, in its pure state, as a shiny white metal. Instead, it has undergone transformations over millions of years that have positioned it as a Li ion.+ (mainly) in certain minerals and rock groups.
It is estimated that its concentration in the earth's crust ranges between 20 and 70 ppm (part per million), which is equivalent to approximately 0.0004% of it. While in marine waters, its concentration is in the order of 0.14 and 0.25 ppm; that is, lithium is more abundant in stones and minerals than in brines or sea beds.
The minerals where this metal is found are the following:
- Spodumene, LiAl (SiO3)two
- Petalite, LiAlSi4OR10
- Lepidolite, K (Li, Al, Rb)two(Al, yes)4OR10(F, OH)two
These three minerals have in common that they are lithium aluminosilicates. There are other minerals where the metal can also be extracted, such as ambligonite, elbaite, tripillite, eucriptite, or hectorite clays. However, spodumene is the mineral from which the largest amount of lithium is produced. These minerals make up some igneous rocks such as granite or pegmatite.
In relation to the sea, it is extracted from brines as lithium chloride, hydroxide or carbonate, LiCl, LiOH and LitwoCO3, respectively. In the same way it can be obtained from lakes or lagoons, or in different brine deposits.
In total, lithium is ranked 25th in abundance of the elements on Earth, which correlates well with its low concentration in both land and water, and is therefore considered a relatively rare element..
Lithium is found in young stars, in greater abundance than in older stars.
In order to obtain or produce this metal in its pure state, there are two options (ignoring the economic or profitability aspects): extract it by mining action or collect it in brines. The latter is the predominant source in the production of metallic lithium..
A molten LiCl mixture is obtained from the brine, which can then be subjected to electrolysis to separate the salt into its elemental components:
LiCl (l) → Li (s) + 1/2 Cltwo(g)
While minerals are digested in acidic media to obtain their Li ions+ after separation and purification processes.
Chile is positioned as the largest lithium producer in the world, obtaining it from the Atacama salt flat. On the same continent, Argentina follows, a country that extracts LiCl from the Salar del Hombre Muerto and, finally, Bolivia. However, Australia is the largest lithium producer through the exploitation of spodumene.
The best known reaction of lithium is the one that occurs when it comes into contact with water:
2Li (s) + 2HtwoO (l) → 2LiOH (aq) + Htwo(g)
LiOH is lithium hydroxide and, as can be seen, produces hydrogen gas.
Reacts with gaseous oxygen and nitrogen to form the following products:
4Li (s) + Otwo(g) → 2LitwoYou)
2Li (s) + Otwo(g) → 2LitwoORtwo(s)
The LitwoOr is it lithium oxide, which tends to form on top of LitwoORtwo, peroxide.
6Li (s) + Ntwo(g) → 2Li3N (s)
Lithium is the only alkali metal capable of reacting with nitrogen and giving rise to this nitride. In all these compounds the existence of the Li cation can be assumed+ participating in ionic bonds with covalent character (or vice versa).
It can also react directly and vigorously with halogens:
2Li (s) + Ftwo(g) → LiF (s)
Also reacts with acids:
2Li (s) + 2HCl (conc) → 2LiCl (aq) + Htwo(g)
3Li (s) + 4HNO3(dilute) → 3LiNO3(aq) + NO (g) + 2HtwoO (l)
The compounds LiF, LiCl and LiNO3 are lithium fluoride, chloride and nitrate, respectively.
And regarding its organic compounds, the best known is lithium butyl:
2 Li + C4H9X → C4H9Li + LiX
Where X is a halogen atom and C4H9X is an alkyl halide.
Lithium reacts violently with water and can react with moisture on the skin. That is why if someone handled it with their bare hands they would suffer burns. And if it is granular or in powder form, it catches fire at room temperature, thus posing fire hazards..
Gloves and safety glasses should be used to handle this metal, since minimal contact with the eyes could cause severe irritation..
If inhaled, the effects can be even worse, burning the airways and causing pulmonary edema due to the internal formation of LiOH, a caustic substance..
This metal must be stored submerged in oil, or in dry atmospheres and more inert than nitrogen; for example in argon, as shown in the first picture.
Compounds derived from lithium, especially its salts, such as carbonate or citrate, are much safer. That as long as the people who ingest them respect the indications prescribed by their doctors..
Some of the many undesirable effects that it can generate in patients are: diarrhea, nausea, fatigue, dizziness, lightheadedness, tremors, excessive urination, thirst and weight gain.
The effects can be even more serious in pregnant women, affecting the health of the fetus, or increasing birth defects. Likewise, its intake is not recommended in nursing mothers, since lithium can pass from milk to the baby, and from there develop all kinds of anomalies or negative effects..
The best known uses for this metal at a popular level reside in the area of medicine. However, it has application in other areas, especially in energy storage through the use of batteries..
Lithium salts, specifically LitwoCO3, serves as an additive in foundry processes for different purposes:
-Degass
-Desulfurizes
-Refines grains of non-ferrous metals
-Increases the fluidity of the slags in the casting molds
-Reduces the melting temperature in aluminum castings thanks to its high specific heat.
Alkyl lithium compounds are used to alkylate (add R side chains) or arylar (add Ar aromatic groups) molecular structures. They stand out for their good solubility in organic solvents and for not being so reactive in the reaction medium; therefore, it serves as reagents or catalysts for multiple organic syntheses.
Lithium stearate (product of the reaction between a grease and LiOH) is added to the oil to create a lubricating mixture.
This lithium lubricant is resistant to high temperatures, does not harden when cooled, and is inert to oxygen and water. Therefore, it finds use in military, aerospace, industrial, automotive, etc. applications..
Glasses or ceramics that are treated with LitwoOr they acquire lower viscosities when they melt and greater resistance to thermal expansion. For example, kitchen utensils are made of these materials and Pyrex glass also has this compound in its composition..
Because it is such a light metal, so are its alloys; among them, those of aluminum-lithium. When added as an additive, it not only gives them less weight, but also greater resistance to high temperatures.
Its high specific heat makes it ideal to be used as a refrigerant in processes where a lot of heat is released; for example, in nuclear reactors. This is because it "costs" to raise its temperature, and therefore prevents heat from easily radiating to the outside.
And the most promising use of all is in the lithium-ion battery market. These take advantage of the ease with which lithium oxidizes to Li+ to use the released electron and activate an external circuit. Thus, the electrodes are either made of metallic lithium, or of alloys thereof, where the Li+ can intercalate and travel through electrolyte material.
As a final curiosity, the musical group Evanescense, dedicated a song with the title "Lithium" to this mineral.
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