Lithium (Li): Properties & Uses

Lithium element

Lithium is believed to be one of the only three elements produced in significant quantities by the Big Bang. Synthesis of these elements took place within the first 3 minutes of the Universe’s existence. So, let us understand about the oldest element present in the universe. Lithium (in greek means “lithos” which means” stone”) is a chemical element in Group 1 in the periodic table with symbol ‘Li’ and atomic number 3.It is a soft, silvery-white alkali metal. It is lightest metal and lightest solid element under standard conditions.

Properties

Physical Properties

Lithium metal is soft enough to be cut with a knife. When cut possesses a silvery-white colour that quickly changes to grey as it oxidizes to lithium oxide. It has the lowest melting point among all metals (180 °C, 453 K) but has the highest melting and boiling point of the alkali metals. It has a very low density (0.534 g/cm3), comparable with pinewood. Apart from helium and hydrogen, as a solid, it is less dense than any other element as a liquid. It 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.

Silvery white lustre of lithium

The silvery-white lustre of lithium

Atomic Properties

Lithium has a single valence electron that is easily given up to form a cation. Due to this, lithium is a good conductor of heat and electricity as well as a highly reactive element, though it is the least reactive of the alkali metals. However, molten lithium is significantly more reactive than its solid form.

 

Chemical Properties

Lithium reacts with water easily. Because of its reactivity with water, lithium is usually stored in a hydrocarbon sealant, often petroleum jelly. When placed over a flame, lithium compounds give off a striking crimson colour, but when the metal burns strongly, the flame becomes a brilliant silver. Lithium will ignite and burn in oxygen when exposed to water or water vapours. Lithium is flammable, and it is potentially explosive when exposed to air and especially to water, though less so than the other alkali metals. Lithium is one of the few metals that react with nitrogen under normal conditions.

 Diagonal relationship with Magnesium

Lithium has a diagonal relationship with Magnesium, an element of the similar atomic and ionic radius. Both have almost similar electronegativities, and both are harder and lighter than other elements in their respective groups.  The chemical resemblance between the two includes the formation of a nitride by reaction with  N2, the formation of oxide and peroxide when burnt in O2, salts with similar solubilities and thermal instability of the carbonates and nitrides.

Diagonal relationship in Main group elements

Diagonal relationship in Main group elements

Organic chemistry

Organolithium reagents are known in which there is a direct bond between carbon and lithium atoms. These are extremely powerful bases and nucleophiles. They have also been applied in synthesis in the pharmaceutical industry. For laboratory organic synthesis, many organolithium reagents are commercially available in solution form. These reagents are highly reactive.

Example of organolithium reagent

Example of organolithium reagent

Isotopes

Naturally occurring lithium is composed of two stable isotopes, 6Li and 7Li. Lithium is the only low numbered element that can produce net energy through nuclear fission. Though very light in atomic weight, lithium is less common in the Solar System than 25 of the first 32 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. Lithium isotopes fractionate substantially during a wide variety of natural processes, including mineral formation (chemical precipitation), metabolism, and ion exchange. Nuclear weapons manufacture and other nuclear physics applications are a major source of artificial lithium fractionation, with the light isotope 6Li  being retained by industry.

Stable isotopes of Lithium

Stable isotopes of Lithium

Uses

1) Electronics industry

Lithium is an important component of battery electrolytes and electrodes, because of its high electrode potential. Lithium-ion or Li-Ion batteries are a type of rechargeable battery that’s used in many applications, but most commonly in the electronics industry. Li-Ion batteries provide portable electricity, powering electronic gadgets such as mobile phones, laptops and tablets. Li-Ion batteries are also used to supply energy to medical equipment, electric vehicles and power tools. Lithium is the primary source for Li-Ion battery packs as it is more stable and safer in charging and discharging energy compared to other minerals.

2) Ceramics and glass

Enamels and glazes are used to cover metal and ceramics bodies. The addition of lithium carbonate and spodumene in the manufacturing of enamels and glazes have these advantages; (1) it lowers the firing temperatures and thermal expansion, (2) it increases the strength of ceramics bodies, and (3) it improves viscosity for coating, as well as improving the glaze’s colour, strength and lustre. Spodumene is a lithium aluminium silicate and already contains silicon oxide and aluminium oxide, which is a major component in a glass.

Lithium Ceramics

Lithium Ceramics

(3) Lubricating greases

The most common use of lithium is in greases. Lithium hydroxide is a strong base and, when heated with a fat, produces a soap made of lithium stearate. Lithium soap has the ability to thicken oils, and it is used to manufacture all-purpose, high-temperature lubricating greases.

Lithium grease

Lithium grease

 

(4) Medicine

Lithium salts are one of the widely used medication for the treatment of “bipolar disorder” (previously known as manic depression, is a mental disorder characterized by periods of depression and periods of abnormally elevated mood that last from days to weeks). Lithium salts were the first drugs approved by the Food and Drug Administration to treat mania and depression, according to the National Institute of Mental Health. Today, lithium carbonate is the compound most often sold as a pharmaceutical but no one knows exactly how lithium works to stabilize mood.

Lithium drug

 

(5) Air Purification

In confined areas such as abroad Spacecraft and Submarines, lithium hydroxide and lithium peroxide are the salts that are used for carbon dioxide removal and air purification. Lithium hydroxide absorbs carbon dioxide from the air by forming lithium carbonate and is preferred over other alkaline hydroxides due to its low weight. Lithium peroxide (Li2O2) in presence of moisture not only reacts with carbon dioxide to form lithium carbonate but also releases oxygen.

2 Li2O2 + 2 CO2 → 2 Li2CO3 + O2

Lithium as airpurifier in Submarines

Lithium as Air purifier in Submarines

(6) Military applications

Metallic lithium and its complex hydrides, such as Li[AlH4], are used as high-energy additives to rocket propellants. Lithium aluminium hydride can also be used by itself as a solid fuel. Lithium hydride containing lithium-6 is used in thermonuclear weapons, where it serves as fuel for the fusion stage of the bomb.

Rocket Propellents

Rocket Propellents

 

(7) Lithium-Aluminium Alloys

Lithium-Aluminium alloys are primarily of interest to the Aerospace industry. Al–Li alloys are lighter and have high tensile and yield strength compared to the conventional high-strength aluminium alloys. They are resistant to fatigue crack propagation; however, their corrosion resistance still needs to be improved.

Lithium-Aluminium alloy

Lithium-Aluminium alloy

 

Add Comment