Feb 11 2003
Discovered in 1817 by J.A. Arfvedson in Stockholm, Sweden, and isolated by W.T. Brande in 1821.
Lithium (Li) is a soft, silver metal, and is the first member of the alkali group of metals. It is the lightest of all metals and, whilst resembling sodium chemically, it is less active.
Abundance and Production
As is the case for other alkali group elements, Lithium is obtained by the electrolysis of the fused halides. The abundance of lithium in the earth's crust is 20 ppm.
Lithium reacts slowly in water and in air where it eventually forms a black coating of oxide. This means that Lithium tends to be stored under oil to prevent deterioration.
Applications
Lithium is used as an alloying agent with aluminium and magnesium, and in the manufacture of batteries. Compounds of lithium are used in various applications; for example, Lithium 12-hydroxy stearate is used in high performance greases as it provides good water resistance and good low temperature performance; Lithium hydride is a strong reducing agent and is used as a source of hydrogen, and lithium carbonate is used as a tranquiliser and in the treatment of some mental illnesses.
Lithium and its compounds also find applications in the manufacture of glass and ceramics.
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Lithium is also used in the manufacturing of glass Image Credit: FreeProd33/shutterstock
Key Properties
The key properties of Lithium are tabulated below.
Table 1. Key properties
| Atomic Properties |
| Atomic number |
3 |
| Atomic radius - Goldschmidt ( nm ) |
0.157 |
| Atomic weight ( amu ) |
6.941 |
| Crystal structure |
Body centred cubic |
| Electronic structure |
He 2s1 |
| Photo-electric work function ( eV ) |
2.4 |
| Thermal neutron absorption cross-section ( Barns ) |
63 |
| Valences shown |
1 |
| Ionisation potential |
No. |
eV |
| |
1 |
5.39 |
| |
2 |
75.6 |
| |
3 |
122.4 |
| Natural isotope distribution |
Mass No. |
% |
| |
6 |
7.5 |
| |
7 |
92.5 |
| Electrical Properties |
| Electrical resistivity @ 20 °C ( µOhm.cm ) |
9.29 |
| Temperature coefficient @ 0-100 °C ( K-1 ) |
0.00435 |
| Thermal emf against Pt (cold 0 °C - hot 100 °C) ( mV ) |
+1.82 |
| Mechanical Properties |
| Material condition |
Polycrystalline |
| Bulk modulus ( GPa ) |
11.1 |
| Hardness – Vickers |
<5 |
| Poisson’s ratio |
0.36 |
| Tensile modulus ( GPa ) |
4.91 |
| Physical Properties |
| Boiling point (°C ) |
1342 |
| Density @ 20 °C ( g.cm-3 ) |
0.534 |
| Melting point (°C ) |
180.5 |
| Thermal Properties |
| Coefficient of thermal expansion @ 0-100 °C ( x10-6 K-1 ) |
56 |
| Latent heat of evaporation ( J.g-1 ) |
19600 |
| Latent heat of fusion ( J.g-1 ) |
422 |
| Specific heat @ 25 °C ( J.K-1.kg-1 ) |
3560 |
| Thermal conductivity @ 0-100 °C ( W.m-1.K-1 ) |
84.8 |
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