Sodium
Na
Atomic Number - 11
Sodium is relatively abundant in stars and the D spectral lines of
this element are among the most prominent in star light.
The History Says
At the end of the 19th century, sodium was chemically prepared by
heating sodium carbonate with carbon to 1100°C.
Na2CO3 (liquid) + 2C (solid, coke) = 2Na
(vapor) + 3CO (gas).
The Present Scenario
Now, sodium is commercially produced through the electrolysis of
liquid sodium chloride, done in Down's cell where NaCl is mixed with
calcium chloride to make the melting point below 700 °C. Calcium
is more electropositive than sodium, so it is not formed at the
cathode. The method is less expensive.
SODIUM
IS a soft, waxy, silvery reactive metal belonging to the alkali
metals. It is abundant in natural compounds, especially halite. It is
highly reactive and burns with a yellow flame. It reacts violently
with water and oxidizes in air. This is the reason for soring pure
sodium in oil.
In nature sodium never occurs as a pure elemental metal. It floats in
water, reacts violently with it releasing heat, flammable hydrogen gas
and caustic sodium hydroxide solution.
Sodium was long back recognized in compounds as soda but became
isolated in 1807 by Sir Humphry Davy through the electrolysis of
caustic soda. In the medieval Europe, a compound of sodium was used
for the remedy of headach with the Latin name "sodanum." The
symbol 'Na' is derived from the neo-Latin name for a common sodium
compound called "natrium." This is in fact taken from the
Greek "nitron," a kind of natural salt.
Health and Sodium
Sodium ions regulates blood and body fluids, transmission of nerve
impulses, heart activity, and certain metabolic functions. The
deficiency of sodium causes nausea, muscular cramps, dizziness and
prolonged diarrhoea. Retention of water by the kidney is also
affected. Sodium in excess in the body cause hypertension and
increases the risks of heart problems.
Sources of Sodium
The best sources of sodium are table salt, prepared meat, dairy
products, eggs, tuna, salmon, canned food, fruits and vegetables,
Brazil nuts and pastas.
Physical Properties of Sodium
| Phase |
Solid |
| Density (near room temperature) |
0.968 g/cm3 |
| Liquid density at melting point |
0.927 g/cm3 |
| Melting point |
1156 K
(97.72°C, 207.9°F) |
| Boiling point |
1156 K
(883°C, 1621°F) |
| Heat of fusion |
2.60 kJ/mol |
| Heat of vaporization |
97.42 kJ/mol |
| Heat capacity |
(25°C) 28.230 J/(mol-K) |
Atomic Properties of Sodium
| Crystal structure |
Cubic body centered |
| Oxidation states |
1 (strongly basic oxide) |
| Electronegativity |
0.93 (Pauling scale) |
| Ionization energies |
1st: 495.8 kJ/mol
2nd: 4562 kJ/mol
3rd: 6910.3 kJ/mol |
| Atomic radius |
180 pm |
| Atomic radius (calc.) |
190 pm |
| Covalent radius |
154 pm |
| Van der Waals radius |
227 pm |
Applications of Sodium
In metallic form, sodium is an essential component in the making of
esters and manufacturing organic compounds. The alkali metal is also
vital to life. It is a component of sodium chloride (NaCl). Some other
uses are as follows:
- In
some of the alloys in improving their structure.
- In
soap with the combination of fatty acids.
- To
descale or making smooth surface of metal.
- In
the purification of molten metals.
- As
an efficient means of producing light from electricity in sodium
vapor lamps.
- As
heat transfer fluid in some of the nuclear reactors and inside the
hollow valves of high-performance internal combustion engines.
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