Feb 6 2003
Background
Sodium (Na) was discovered in 1807 by Sir Humphrey Davy in London.
Occurrence and Abundance
Along with potassium, Sodium is one of the more common alkali metals, there being 28300 ppm in the earth’s crust, primarily as the carbonate, chloride or nitrate.
Preparation of Sodium Metal
Sodium is a soft, silvery coloured metal which, like other members of the alkali group of metals, is extremely reactive. As for the other members of the group, it can be prepared by electrolysis of the fused halide or hydroxide.
Applications
Molten Sodium is used as a heat exchanger in certain types of nuclear reactors and as a reagent in the chemicals industry. Some of the Sodium salts (e.g. NaCl and NaCO3) are more important than the metal itself due to the variety of applications for which they can be used.
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Nuclear Reactors often use molten sodium as a heat exchanger/ Image Credit:Thorsten Schier/Shutterstock
Sodium and The Human Body
Sodium is an essential element for all living species, including humans, although there is an element of controversy concerning the amount required. An average human body contains around 100 grams of Sodium which are lost in various ways and has to be replenished. The average human consumes approximately 10 grams of salt per day although only around 3 grams are actually needed and an excess can contribute to high blood pressure. Sodium performs several functions within the body including the regulation of the water content in the blood and tissue and the transmission of electrical impulses.
Key Properties
The key properties of Sodium are tabulated below.
Table 1. Key properties
| Atomic Properties |
| Atomic number |
11 |
| Atomic radius - Goldschmidt ( nm ) |
0.192 |
| Atomic weight ( amu ) |
22.99 |
| Crystal structure |
Body centred cubic |
| Electronic structure |
Ne 3s1 |
| Photo-electric work function ( eV ) |
212 |
| Thermal neutron absorption cross-section ( Barns ) |
0.54 |
| Valences shown |
1 |
| Ionisation Potential |
No. |
eV |
| |
1 |
5.14 |
| |
2 |
47.30 |
| |
3 |
71.64 |
| |
4 |
98.91 |
| |
5 |
138.39 |
| |
6 |
172.15 |
| Natural Isotope Distribution |
Mass No. |
% |
| |
23 |
100 |
| Electrical Properties |
| Temperature coefficient @ 0-100 °C ( K-1 ) |
0.0055 |
| Electrical resistivity @^C ( µOhm.cm ) |
4.5 |
| Physical Properties |
| Boiling point (°C ) |
883 |
| Density ( g.cm-3 ) |
0.97 |
| Melting point ( °C ) |
97.8 |
| Thermal Properties |
| Coefficient of thermal expansion @^C ( x10-6 K-1 ) |
71 |
| Latent heat of evaporation ( J.g-1 ) |
4260 |
| Latent heat of fusion ( J.g-1 ) |
113 |
| Thermal conductivity @ 0-100 °C ( W.m-1.K-1 ) |
128 |
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