Everything about Lithium totally explained
Lithium is a
chemical element with the symbol
Li and
atomic number 3. It is a soft
alkali metal with a silver-white color. Under
standard conditions, it's the lightest
metal and the least dense
solid element. Like all alkali metals, lithium is highly reactive,
corroding quickly in moist
air to form a black tarnish. For this reason, lithium metal is typically stored under the cover of
oil.
According to theory, lithium (mostly
7Li) was one of the few elements
synthesized in the
Big Bang, although its quantity has vastly decreased. The reasons for its disappearance and the processes by which new lithium is created continue to be important matters of study in
astronomy. Lithium is the 33rd most abundant element on
Earth, but due to its high
reactivity only appears naturally in the form of
compounds. Lithium occurs in a number of
pegmatitic minerals, but is also commonly obtained from
brines and
clays; on a commercial scale, lithium metal is isolated
electrolytically from a mixture of
lithium chloride and
potassium chloride.
Trace amounts of lithium are present in the
oceans and in some organisms, though the element serves no apparent biological function in humans. Nevertheless, the neurological effect of the lithium ion Li
+ makes some lithium
salts useful as a class of
mood stabilizing drugs. Lithium and its compounds have several other commercial applications, including heat-resistant
glass and
ceramics, high strength-to-weight
alloys used in
aircraft, and
lithium batteries. Lithium also has important links to
nuclear physics: the
splitting of lithium atoms was the first man-made form of
nuclear reaction, and
lithium deuteride serves as the
fusion fuel in
staged thermonuclear weapons.
History and etymology
Petalite (lithium aluminium silicate) was first described in 1800 by the Brazilian scientist
José Bonifácio de Andrade e Silva, who discovered the mineral in a
Swedish iron mine on the island of
Utö. However, it wasn't until 1817 that
Johann August Arfwedson, then a trainee in the laboratory of
Jöns Jakob Berzelius,
discovered the presence of a new element while analyzing petalite ore. The element formed compounds similar to those of
sodium and
potassium, though its
carbonate and
hydroxide were less
water soluble and had a larger capacity to neutralize acid. Berzelius gave the alkaline material the name "lithos", from the
Greek λιθoς (
lithos, "stone"), to reflect its discovery in a mineral, as opposed to sodium and potassium which had been discovered in
plant tissue; its name would later be standardized as "lithium". Arfwedson later showed that this same element was present in the mineral ores
spodumene and
lepidolite. In
1818,
Christian Gmelin was the first to observe that lithium salts give a bright red color in flame. However, both Arfwedson and Gmelin tried and failed to isolate the element from its salts.
The element wasn't isolated until 1821, when
William Thomas Brande performed
electrolysis on
lithium oxide, a process which had previously been employed by
Sir Humphry Davy to isolate potassium and sodium. Brande also described pure salts of lithium, such as the chloride, and performed an estimate of its atomic weight. In 1855,
Robert Bunsen and Augustus Matthiessen produced large quantities of the metal by electrolysis of
lithium chloride. Commercial production of lithium metal began in
1923 by the German company
Metallgesellschaft AG through the electrolysis of a molten mixture of lithium chloride and
potassium chloride.
Properties
Like other
alkali metals, lithium has a single
valence electron which it'll readily lose to form a
cation, indicated by the element's low
electronegativity. As a result, lithium is easily deformed, highly reactive, and has lower
melting and
boiling points than most metals. These and many other properties attributable to alkali metals' weakly-held valence electron are most distinguished in lithium, as it possesses the smallest
atomic radius and thus the highest electronegativity of the alkali group. In addition, lithium has a
diagonal relationship with
magnesium, an element of similar atomic and
ionic radius. Chemical resemblances between the two metals include the formation of a
nitride in N
2, the formation of an
oxide when burnt in O
2,
salts with similar
solubilities, and thermally-unstable
carbonates and nitrides.
Lithium is soft enough to be cut with a knife, though this is more difficult than cutting sodium. The fresh metal has a silvery-white color which only remains untarnished in dry air. Seven
radioisotopes have been characterized, the most stable being
8Li with a
half-life of 838
ms and
9Li with a half-life of 178.3 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 7.58043x10
-23 s.
7Li is one of the
primordial elements or, more properly, primordial isotopes, produced in
Big Bang nucleosynthesis (a small amount of
6Li is also produced in stars). Lithium isotopes fractionate substantially during a wide variety of natural processes, including mineral formation (chemical precipitation),
metabolism, and
ion exchange. Lithium ion substitutes for
magnesium and
iron in octahedral sites in
clay minerals, where
6Li is preferred to
7Li, resulting in enrichment of the light isotope in processes of hyperfiltration and rock alteration. The exotic
11Li is known to exhibit a
nuclear halo.
Natural occurrence
See also .
Lithium is widely distributed on Earth and is the 33rd most abundant element;
The high non-linearity of lithium niobate also makes a good choice for non-linear optics applications.
Lithium deuteride was the fusion fuel of choice in early versions of the hydrogen bomb. When bombarded by neutrons, both 6Li and 7Li produce tritium—this reaction, which wasn't fully understood when hydrogen bombs were first tested, was responsible for the runaway yield of the Castle Bravo nuclear test. Tritium fuses with deuterium in a fusion reaction that's relatively easy to achieve. Although details remain secret, lithium-6 deuteride still apparently plays a role in modern nuclear weapons, as a fusion material.
Metallic lithium and its complex hydrides such as for example Li[AlH4] are considered as high energy additives to rocket propellants[3].
Lithium peroxide, lithium nitrate, lithium chlorate and lithium perchlorate are used and thought of as oxidizers in both rocket propellants and oxygen candles to supply submarines and space capsules with oxygen.
Lithium will be used to produce tritium in magnetically confined nuclear fusion reactors using deuterium and tritium as the fuel. Tritium doesn't occur naturally and will be produced by surrounding the reacting plasma with a 'blanket' containing lithium where neutrons from the deuterium-tritium reaction in the plasma will react with the lithium to produce more tritium. 6Li + n → 4He + 3H. Various means of doing this will be tested at the ITER reactor being built at Cadarache, France.
Lithium is used as a source for alpha particles, or helium nuclei. When 7Li is bombarded by accelerated protons, 8Be is formed, which undergoes spontaneous fission to form two alpha particles. This was the first man-made nuclear reaction, produced by Cockroft and Walton in 1929.
Lithium hydroxide (LiOH) is an important compound of lithium obtained from lithium carbonate (Li2CO3). It is a strong base, and when heated with a fat, it produces a lithium soap. Lithium soap has the ability to thicken oils and so is used commercially to manufacture lubricating greases.
It is also an efficient and lightweight purifier of air. In confined areas, such as aboard spacecraft and submarines, the concentration of carbon dioxide can approach unhealthy or toxic levels. Lithium hydroxide absorbs the carbon dioxide from the air by reacting with it to form lithium carbonate. Any alkali hydroxide will absorb CO2, but lithium hydroxide is preferred, especially in spacecraft applications, because of the low formula weight conferred by the lithium. Even better materials for this purpose include lithium peroxide (Li2O2) that, in presence of moisture, not only absorb carbon dioxide to form lithium carbonate, but also release oxygen. E.g. 2 Li2O2 + 2 CO2 → 2 Li2CO3 + O2.
Lithium metal is used as a reducing agent in some types of methamphetamine production, particularly in illegal amateur “meth labs.”
Lithium can be used to make red fireworks
A Bose-Einstein Condensate of Lithium was achieved in 1995.
Production
Since the end of World War II, lithium metal production has greatly increased. The metal is separated from other elements in igneous mineral such as those above, and is also extracted from the water of mineral springs.
The metal is produced electrolytically from a mixture of fused lithium and potassium chloride. In 1998 it was about US$ 43 per pound ($95 per kg).
Chile is currently the leading lithium metal producer in the world, with Argentina next. Both countries recover the lithium from brine pools. In the United States lithium is similarly recovered from brine pools in Nevada.
China may emerge as a significant producer of brine-based lithium carbonate around 2010. Potential capacity of up to 45,000 tonnes per year could come on-stream if projects in Qinghai province and Tibet proceed.
Precautions
Lithium metal, due to its alkaline tarnish, is corrosive and requires special handling to avoid skin contact. Breathing lithium dust or lithium compounds (which are often alkaline) can irritate the nose and throat; higher exposure to lithium can cause a build-up of fluid in the lungs, leading to pulmonary edema. The metal itself is usually a handling hazard because of the caustic hydroxide produced when it's in contact with moisture. Lithium should be stored in a non-reactive compound such as naphtha or a hydrocarbon.
Regulation
Some jurisdictions limit the sale of lithium batteries, which are the most readily available source of lithium metal for ordinary consumers. Lithium can be used to reduce pseudoephedrine and ephedrine to methamphetamine in the Birch reduction method, which employs solutions of alkali metals dissolved in anhydrous ammonia. However, the effectiveness of such restrictions in controlling illegal production of methamphetamine remains indeterminate and controversial.
Carriage and shipment of some kinds of lithium batteries may be prohibited aboard certain types of transportation (particularly aircraft), because of the ability of most types of lithium batteries to fully discharge very rapidly when short-circuited, leading to overheating and possible explosion. However, most consumer lithium batteries have thermal overload protection built-in to prevent this type of incident, or their design inherently limits short-circuit currents.
Further Information
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