Alkali metal
Lithium (from Ancient Greek: λίθος, líthos, 'stone') is a chemical element; it has symbol Li and atomic number 3. It is a soft, silvery-white alkali metal. Under standard conditions, it is the least dense metal and the least dense solid element. Like all alkali metals, lithium is highly reactive and flammable, and must be stored in vacuum, inert atmosphere, or inert liquid such as purified kerosene or mineral oil. It exhibits a metallic luster when pure, but quickly corrodes in air to a dull silvery gray, then black tarnish. It does not occur freely in nature, but occurs mainly as pegmatitic minerals, which were once the main source of lithium. Due to its solubility as an ion, it is present in ocean water and is commonly obtained from brines. Lithium metal is isolated electrolytically from a mixture of lithium chloride and potassium chloride.
The nucleus of the lithium atom verges on instability, since the two stable lithium isotopes found in nature have among the lowest binding energies per nucleon of all stable nuclides. Because of its relative nuclear instability, lithium is less common in the Solar System than 28 of the first 34 chemical elements even though its nuclei are very light: it is an exception to the trend that heavier nuclei are less common. For related reasons, lithium has important uses in nuclear physics. …
Petalite (LiAlSi4O10) was discovered in 1800 by the Brazilian chemist and statesman José Bonifácio de Andrada e Silva in a mine on the island of Utö, Sweden. However, it was not until 1817 that Johan August Arfwedson, then working in the laboratory of the chemist Jöns Jakob Berzelius, detected the presence of a new element while analyzing petalite ore. This element formed compounds similar to those of sodium and potassium, though its carbonate and hydroxide were less soluble in water and less alkaline. Berzelius gave the alkaline material the name "lithion/lithina", from the Greek word λιθoς (transliterated as lithos, meaning "stone"), to reflect its discovery in a solid mineral, as opposed to potassium, which had been discovered in plant ashes, and sodium, which was known partly for its high abundance in animal blood. He named the new element "lithium".
Arfwedson later showed that this same element was present in the minerals spodumene and lepidolite. In 1818, Christian Gmelin was the first to observe that lithium salts give a bright red color to flame. However, both Arfwedson and Gmelin tried and failed to isolate the pure element from its salts. It was not isolated until 1821, when William Thomas Brande obtained it by electrolysis of lithium oxide, a process that had previously been employed by the chemist Sir Humphry Davy to isolate the alkali metals potassium and sodium. …
The alkali metals are also called the lithium family, after its leading element. Like the other alkali metals (which are sodium (Na), potassium (K), rubidium (Rb), caesium (Cs), and francium (Fr)), lithium has a single valence electron that, in the presence of solvents, is easily released to form Li+. Because of this, lithium is a good conductor of heat and electricity as well as being chemically reactive, though it is the least reactive of the alkali metals. Lithium's lower reactivity is due to the proximity of its valence electron to its nucleus (the remaining two electrons are in the 1s orbital, much lower in energy, and do not participate in chemical bonds). Molten lithium is significantly more reactive than its solid form.
Lithium metal is soft enough to be cut with a knife. It is silvery-white. In air it oxidizes to lithium oxide. Its melting point of 180.50 °C (453.65 K; 356.90 °F) and its boiling point of 1,342 °C (1,615 K; 2,448 °F) are each the highest of all the alkali metals.
Lithium has the lowest density (0.534 g/cm3) of all metals under standard conditions. Lithium can float on the lightest hydrocarbon oils and is one of only three metals that can float on water, the other two being sodium and potassium.
Lithium's coefficient of thermal expansion is twice that of aluminium and almost four times that of iron. Lithium is superconductive below 400 μK at standard pressure and at higher temperatures (more than 9 K) at very high pressures (>20 GPa). …
Lithium-7 was created in nuclear reactions very early in the history of the universe, in a process called Big Bang nucleosynthesis. The relative amount of lithium was small compared to isotopes of hydrogen and helium. The only other element created was beryllium-7 which decayed into lithium-7. Measured lithium abundance does not match the nucleosynthesis model well, an issue called "cosmological lithium problem"; whether this is due to issues in the difficult experimental measurements or in aspects of the theory is not known. Measurements of primordial lithium abundance are complicated because lithium-7 can be created and destroyed in cosmic ray, classical nova, and supernova reactions, and inside stars. The only known mechanism to produce lithium-6 is via cosmic-ray interactions.
Lithium is also found in brown dwarf substellar objects. Because lithium is present in cooler, less-massive brown dwarfs, but is destroyed in hotter red dwarf stars, its presence in the stars' spectra can be used in the lithium test to differentiate them. Certain red giant stars can also contain a high concentration of lithium. Many different causes have been proposed for this lithium, including pulling lithium from companion stars.
Although lithium is widely distributed on Earth, it does not naturally occur in elemental form due to its high reactivity. …
In 2026, 88% of the worlds lithium production was used to make lithium-ion batteries.
Lithium-ion batteries have become essential in modern technology powering things such as electric cars, portable electronics, and satellites. In the 20th century, lithium became an important component of battery electrolytes and electrodes because of its high electrode potential. Other rechargeable batteries that use lithium include the lithium polymer battery and the lithium iron phosphate battery.
The second largest use of lithium compounds, accounting for 4% of lithium worldwide, is in the production of ceramics and glass. Lithium oxide is widely used as a flux for processing silica, reducing the melting point and viscosity of the material and leading to glazes with improved physical properties including low coefficients of thermal expansion. Glazes containing lithium oxides are used for ovenware. Lithium carbonate (Li2CO3) is generally used in this application because it converts to the oxide upon heating.
The third most common use of lithium is in greases. Lithium hydroxide is a strong base, and when heated with a fat, it produces a soap, such as lithium stearate from stearic acid. Lithium soap has the ability to thicken oils, and it is used to manufacture all-purpose, high-temperature lubricating greases.
Lithium (e.g. …
Naturally occurring lithium is composed of two stable isotopes, 6Li and 7Li, the latter being the more abundant (95.15% natural abundance). Both natural isotopes have anomalously low nuclear binding energy per nucleon (compared to the neighboring elements on the periodic table, helium and beryllium); lithium is the only low numbered element that can produce net energy through nuclear fission. The two lithium nuclei have lower binding energies per nucleon than any other stable nuclides other than hydrogen-1, deuterium and helium-3. As a result of this, though very light in atomic weight, lithium is less common in the Solar System than 28 of the first 34 chemical elements. Seven radioisotopes have been characterized, the most stable being 8Li with a half-life of 838 ms and 9Li with a half-life of 178 ms. All of the remaining radioactive isotopes have half-lives that are shorter than 8.6 ms. The shortest-lived isotope of lithium is 4Li, which decays through proton emission and has a half-life of 7.6 × 10−23 s. The 6Li isotope is one of only five stable nuclides to have both an odd number of protons and an odd number of neutrons, the other four stable odd-odd nuclides being hydrogen-2, boron-10, nitrogen-14, and tantalum-180m.
Lithium isotopes fractionate substantially during a wide variety of natural processes, including mineral formation (chemical precipitation), metabolism, and ion exchange. …
Lithium is found in trace amount in numerous plants, plankton, and invertebrates, at concentrations of 69 to 5,760 parts per billion (ppb). In vertebrates the concentration is slightly lower, and nearly all vertebrate tissue and body fluids contain lithium ranging from 21 to 763 ppb. Marine organisms tend to bioaccumulate lithium more than terrestrial organisms. Whether lithium has a physiological role in any of these organisms is unknown.
Lithium concentrations in human tissue averages about 24 ppb (4 ppb in blood, and 1.3 ppm in bone).
Lithium is easily absorbed by plants and lithium concentration in plant tissue is typically around 1 ppm. Some plant families bioaccumulate more lithium than others. Dry weight lithium concentrations for members of the family Solanaceae (which includes potatoes and tomatoes), for instance, can be as high as 30 ppm while this can be as low as 0.05 ppb for corn grains.
Studies of lithium concentrations in mineral-rich soil give ranges between around 0.1 and 50−100 ppm, with some concentrations as high as 100−400 ppm, although it is unlikely that all of it is available for uptake by plants.
Lithium accumulation does not appear to affect the essential nutrient composition of plants. Tolerance to lithium varies by plant species and typically parallels sodium tolerance; maize and Rhodes grass, for example, are highly tolerant to lithium injury while avocado and soybean are very sensitive. …