The anomalous behaviour of lithium is due to its cation’s small size. Because of its small size and solid nuclear charge, lithium is the most polar alkali metal on negative ions. Thus, lithium-ion has a solid tendency to solvate and form covalent compounds. Li is distinct from other alkali metals because:

• Dry air melting maintains its brilliance.
• No air affects it.
• It slowly decomposes water to produce H2.
• It is more complex than other alkali metals.
• It doesn’t react with bromine like other alkali metals.
• Only lithium reacts directly with N2.
• When heated in NH3, lithium forms Li2 NH, whereas other metals form MNH2.

Let us learn more about the anomalous behaviour of lithium.

What is lithium?

Lithium, along with hydrogen and helium, is one of the leading chemical elements formed during the early stages of the world’s creation. 

• It has an atomic weight of 6.941 and an electron configuration of [He] 2s1. 
• It is also in the s block and has melt and boiling points of 180.50°C and 1330°C, respectively. 
• It is a silvery-white metal that burns with a crimson flame.
• This metal is light and soft to cut with a knife
• It may also float on water, causing an explosive chemical reaction.
• No other alkali metal possesses the qualities of lithium.

Other Alkali Metals

Except for hydrogen, alkali metals are Group 1 elements in the periodic table, and this group comprises the elements potassium, rubidium, caesium, lithium, sodium, and francium. We call them alkali metals because they generate alkali compounds.

Their outermost electron is in an s orbital, which places them in the periodic table’s block, and their most stable charged species is the monovalent cation.

Uses of Lithium

• Doctors use lithium in bipolar disorder medication, and the Food and drug administration has approved its use because it helps patients calm down rapidly. 
• Many doctors prescribe lithium as an antidepressant. But you must first try alternative drugs before switching to a lithium-based dose.
• Without lithium, none of the smartphones you see today would be able to exist in your pockets. Lithium is the solution to all our battery issues; it is light and rechargeable. The Lithium-Ion battery has no current rivals, and it has been a consumer favourite since 1990 and has no problems.
• Aluminium-Lithium alloy built the Tour de France bikes, which are lightweight and robust.
• Lithium oxide is used in the manufacturing of special glasses.
• When you light a firecracker or an air rocket, the red colour comes out when it bursts from lithium.

Chemical properties

Lithium has many properties like the alkali metals sodium and potassium. Floating lithium forms robust hydroxide solutions with water, resulting in LiOH and hydrogen gas. No alkali metal forms the anion Li- in solution or solid except lithium.

Lithium quickly loses one of its three electrons to produce Li+ cations, a chemically active metal. When compared to the corresponding compounds of the other alkali metals, several of them show significant differences in insolubility. Lithium carbonate (Li2CO3) is soluble in both hot and cold water. Inflammable lithium compounds produce a red flame because they react with air moisture.

Organolithium compounds are helpful in other organic compounds. Butyllithium (C4H9Li) reacts with metallic lithium to form butyl bromide (C4H9Br).

Lithium has properties of alkaline-earth elements, such as magnesium, which has similar ionic and atomic radii. Similar oxidation properties, with monoxide, typically formed in each case. Organolithium reactions are identical to the Grignard reactions of organomagnesium compounds, a well-known synthetic procedure in organic chemistry.

Reacting lithium carbonate with lime produces Lithium hydroxide (LiOH). It makes stearic and other fatty acid lithium salts (soaps), widely used as thickeners in lubricating greases. Lithium hydroxide is in alkaline batteries and as a CO2 absorbent. Other critical industrial compounds include lithium chloride (LiCl) and lithium bromide (LiBr). They produce concentrates that may collect moisture from the air at various temperatures. Fluxing enamels and glasses using lithium fluoride.

Nuclear properties

Lithium contains two isotopes of mass number 6 (92.5 per cent) and 7 (7.5 per cent) that have no natural radioactivity. The ratio of lithium-7 / lithium-6 is between 12 and 13.

In 1932, British physicist John Cockcroft and Irish physicist Ernest Walton used lithium as the target metal to transmute nuclei by artificially accelerating atomic particles. Helium and Tritium (3H) are produced when bombarded with lithium-6 with slow neutrons, and this reaction is a primary source of tritium production. Tritium is a radioactive hydrogen isotope that scientists use to make hydrogen bombs and other uses, including a radioactive hydrogen isotope for biological research.

Lithium can be used as a heat-transfer fluid in nuclear reactors with high power densities. The more common stable isotope, lithium-7, has a low atomic cross-section and hence has potential as the primary coolant for atomic reactors that require coolant temperatures above 800 °C (1,500 °F). Nuclear bombardment produces the isotopes lithium-8 (half-life 0.855 seconds) and lithium-9 (half-life 0.17 seconds).

Conclusion

Lithium is very electropositive, and it may create covalent bonds, and its ion behaves like magnesium ion in terms of polarisation. Magnesium and lithium have a diagonal relationship, and they have a diagonal relationship for numerous reasons. An element’s electropositive nature increases from top to bottom in a group and decreases from left to right in a period. It is why we observe similarities in the properties of diagonal elements.

The size of atoms in a group increases from top to bottom, resulting in the element’s polarising power decreasing. However, moving from left to right increases this polarising power, and that’s why diagonal elements have similar properties. Thus, lithium is a vital element, like magnesium.

Their ions are similar in boiling and melting, and weak ionisation energy due to the atom’s small size Water and liquid bromine react. Unlike other alkali metals, it forms a stable hydride.