| Sodium - Na
CAS: 7440-23-5 Description: Soft, silvery-white metal Classification:Alkali Metal Date of Discovery: 1807 Discoverer: Sir Humphrey Davy Name Origin: English, soda; Medieval Latin, sodanum, "headache remedy" Symbol Origin: Latin natrium, "sodium" |
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Atomic Number: 11
Number of Neutrons: 12 Atomic Mass: 22.9897768(6) amu Melting Point: 97.72 ± 0.03 °C Boiling Point: 883 °C Density (293 K): 0.971 g/cm3 Atomic volume: 23.7 cm3/mol Electrical resistivity: 0.139 10-6/cm 
Thermal conductivity: 1.41 W/cmK Enthalpy of atomization: 108.37 kJ/mol Enthalpy of vaporization: 96.960 kJ/mol Enthalpy of fusion: 2.598 kJ/mol Specific heat capacity: 1.23 J/gK |
Energy levels: 2-8-1
Electron configuration: [Ne]3s1 Crystal Structure: Cubic body centered Atomic radius: 2.23 Å Covalent radius: 1.54 Å Oxidation States: +1 Electronegativity, Pauling: 0.93 Electron affinity: 0.547926 eV First ionization energy: 5.139 eV 2nd ionization energy: 47.286 eV 3rd ionization energy: 71.641 eV Polarizability: 24.08 10-24cm3 |
| Isotope | Natural Abundance | Atomic Mass | Half-life | Decay Mode | Spin |
| 19Na | 19.01388 | 0.03 s |  +, p |
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| 20Na | 20.00735 | 0.446 s | +;  |
2+ | |
| 21Na | 20.997655 | 22.48 s | + |
3/2+ | |
| 22Na | 21.994437 | 2.605 y | +; EC |
3+ | |
| 23Na | 100. | 22.9897697 | Stable | 3/2+ | |
| 24mNa | 20.2 ms | IT, - |
1+ | ||
| 24Na | 23.9909633 | 14.96 h | - |
4+ | |
| 25Na | 24.989954 | 59.3 s | - |
5/2+ | |
| 26Na | 25.99259 | 1.07 s | - |
3+ | |
| 27Na | 26.99401 | 0.290 s | -, n |
5/2+ | |
| 28Na | 27.9989 | 31 ms | -; -, n |
1+ | |
| 29Na | 29.0028 | 44 ms | -, n |
3/2+ | |
| 30Na | 30.0092 | 50 ms | - |
2 | |
| 31Na | 31.0136 | 7.2 ms | -, n |
(3/2-) | |
| 32Na | 32.0197 | 13.5 ms | - |
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| 33Na | 33.027 | 8.1 ms | - |
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| 34Na | 34.035 | 5 ms | - |
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| 35Na | 35.044 | 1.5 ms | - |
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Long recognized in compounds, sodium was first isolated by Davy in 1807 by electrolysis of caustic soda. Sodium is present in fair abundance in the sun and stars. The D lines of sodium are among the most prominent in the solar spectrum. Sodium is the sixth most abundant element on earth, comprising about 2.6% of the earth's crust; it is the most abundant of the alkali group of metals of which it is a member. The most common compound is sodium chloride, but it occurs in many other minerals, such as soda niter NaNO3, cryolite (Na3AlF6), amphibole, zeolite, sodalite [Na4Al3(SiO4)3Cl], etc. It is a very reactive element and is never found free in nature. It is now
obtained commercially by the electrolysis of absolutely dry fused sodium chloride. This method is much cheaper than that of electrolyzing sodium hydroxide, as was used several years ago. Sodium is a soft, bright, silvery metal which floats on water, decomposing it with the evolution of hydrogen and the formation of the hydroxide. It may or may not ignite spontaneously on water, depending on the amount of oxide and metal exposed to the
water. It normally does not ignite in air at temperatures below 115 °C. Sodium should be handled with respect, as it can be dangerous when improperly handled. Metallic sodium is vital in the manufacture of sodamide and esters, and in the preparation of organic compounds. The metal may be used to improve the structure of certain alloys, to descale metal, to purify molten metals, and as a heat transfer agent. An alloy of sodium with
potassium, NaK, is also an important heat transfer agent. Sodium compounds are important to the paper, glass, soap, textile, petroleum, chemical, and metal industries. Soap is generally a sodium salt of certain fatty acids. The importance of common salt to animal nutrition has been recognized since prehistoric times. Among the many compounds that are of the greatest industrial importance are common salt (NaCl), soda ash (Na2CO3), baking soda (NaHCO3), caustic soda (NaOH), Chile saltpeter (NaNO3), di- and tri-sodium phosphates, sodium thiosulfate (Na2S2O3 · 5H2O), sodium hypochlorite (bleach, NaOCl), and borax (Na2B4O7 · 10H2O). Seventeen isotopes of sodium are recognized. Metallic sodium is priced at about $250/kg (99.95%). On a volume basis, it is the cheapest of all metals. Sodium metal should be handled with great care. It should be kept in an inert atmosphere and contact with water and other substances with which sodium reacts should be avoided.
LINKS: Arm & Hammer® Baking Soda Chlorox®.com The Oldest Salt Mine in the World Morton International, Inc. Scouting for Sodium And Other Nutrients Important to Blood Pressure The Sodium Chloride Structure The Zeolite Web Return
Sources for the information on this website include: Lide, David R., ed. CRC Handbook of Chemistry and Physics, 78th Ed., 1997-1998. |
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