Lithium: the first metal in the periodic table
How it was discovered and where it's used
Lithium is the third element in the periodic table, and is an alkaline metal. It has a silvery-white color. Lithium is so soft that it can easily be cut with a knife, and has the lowest density of all metals – 0.533 g/cm³ – almost twice as light as water, which means that it floats in water. Lithium has the highest melting and boiling points of all alkaline metals: 180.54 and 1340 °C, respectively. Compared with its neighbors in the group, lithium is the least reactive, and does not react so actively with water and air.
Where lithium is encountered
Lithium has two stable isotopes – lithium-6 and lithium-7 – and was among the first three elements formed in the first seconds after the Big Bang. Now it is contained in greater quantities in young stars, while old stars seem to have less lithium than they should. This may be because in old stars lithium “mixes” into the interior of the star, where it is destroyed. There is a considerable quantity of lithium in orange stars and brown dwarfs.
Lithium is widespread on Earth, but only found in bonded form because of its reactivity. Its content in seawater is 0.14 – 0.25 ppm, and up to 7 ppm near hydrothermal vents. There are rare natural springs of mineral water with high lithium content. This “lithium brine” is called lithia. Lithium is the 25th most abundant element in the earth’s crust. The main minerals that contain lithium are spodumene, petalite, lepidolite and hectorite clay.
How lithium was discovered
In 1800, the Brazilian chemist and statesman José Bonifácio de Andrade e Silva discovered petalite (LiAlSi₄O₁₀) in a mine on the island of Utö, Sweden. While studying petalite ore in the laboratory of Berzelius, the Swedish chemist Johan August Arfwedson detected the presence of a new element. This element had properties similar to sodium and potassium, but its carbonate and hydroxide were less soluble in water and more alkaline. Berzelius proposed to call it “lithion” or “lithina” from the Greek “λιθoς” – stone. He later decided to call the metal lithium. Arfwedson continued to study various minerals, and showed that lithium was contained in spodumene and lepidolite.
In 1818, the German chemist Christain Gmelin discovered that lithium salts turned flames bright red. Both Arfwedson and Gmelin unsuccessfully tried to extract pure lithium, but with no result. It was not extracted until 1821, by William Thomas Brande in England, who became a chemist after he met Humphry Davy. Brande used the method employed by Davy to extract sodium and potassium – electrolysis. From lithium oxide, Brande obtained pure lithium. Additionally, he described some pure salts of lithium, such as the chloride, and estimated the atomic weight of lithium, if somewhat incorrectly: 9.8 instead of 6.94 g/mol.
Where lithium is used
Lithium found its first application in aviation during WWII, and later as a high-temperature engine lubricant. During the Cold War, lithium-6 and lithium-7 isotopes were used in creating the hydrogen bomb, as they produce tritium when irradiated by neutrons. Lithium deuteride was used as solid fusion fuel in hydrogen bombs. After the nuclear arms race came to an end, the production of lithium decreased somewhat.
A new phase in the history of lithium use came from the development and marketing of lithium ion batteries in the late 20th century. Lithium has a low atomic mass with a high potential of electrodes and a high energy-to-weight ratio. There are both chargeable lithium ion batteries and disposable lithium batteries, in which lithium acts as the anode. Other spheres in which lithium is used include the manufacture of ceramics and glazing, metallurgy, where lithium is used in compounds in processes of forging iron, treating aluminum, welding and soldering, as a flux. Lithium hydroxide and peroxide are used for purifying air of carbon dioxide, and also for producing oxygen from CO₂ and lithium peroxide, a process which is used on spacecraft and in submarines. Lithium fluoride is used in IR, UV and vacuum UV optics. If finely divided lithium fluoride powder is exposed to radiation, it releases a bluish light, whose intensity is proportional to the absorbed dose. Lithium fluoride is used in this way in the thermoluminscent radiation dosimetry. It is also used in telescope lenses.
Lithium aluminum hydride, lithium triethylborohydride, n- and tert-butyllithium are widely used reducing agents in organic chemistry.
Additionally, lithium aluminum hydride is used as rocket fuel for military purposes. Lithium carbonate was the first mood-stabilizing drug to reduce symptoms of affective disorders (manic and hypomanic phases of bipolar disorder), and also to treat depression. Later other lithium salts also began to be used in medicine: lithium citrate, succinate, orotate, chloride and sulfate. There is some evidence that the healing properties of lithium salts were first discovered in the 2nd century BCE, when the doctor Soranus of Ephesus treated patients suffering from “mania” and “melancholy” with alkaline water with a high lithium content.
In 1920, Charles Leiper Grigg invented a formula for a lemon-lime soft drink and called it “Bib-Label Lithiated Lemon-Lime Soda”. It contained lithium citrate and was patented as a medicine product. All American beverage makers were subsequently forced to remove lithium additives from their products. The drink was soon changed to “7 Up”.