Media. such as soil. that contains sufficient exchangeable sodium to interfere with the growth of most plants. either with or without appreciable quantities of soluble salts
Sodium is a chemical element; it has symbol Na (from Neo-Latin natrium) and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 of the periodic table. Its only stable isotope is 23Na. The free metal does not occur in nature and must be prepared from compounds. Sodium is the sixth most abundant element in the Earth's crust and exists in numerous minerals such as feldspars, sodalite, and halite (NaCl). Many salts of sodium are highly water-soluble: sodium ions have been leached by the action of water from the Earth's minerals over eons, and thus sodium and chlorine are the most common dissolved elements by weight in the oceans.
Sodium | ||||||||||||||||||||||||||
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Appearance | silvery white metallic | |||||||||||||||||||||||||
Standard atomic weight Ar°(Na) | ||||||||||||||||||||||||||
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Sodium in the periodic table | ||||||||||||||||||||||||||
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Atomic number (Z) | 11 | |||||||||||||||||||||||||
Group | group 1: hydrogen and alkali metals | |||||||||||||||||||||||||
Period | period 3 | |||||||||||||||||||||||||
Block | s-block | |||||||||||||||||||||||||
Electron configuration | [Ne] 3s1 | |||||||||||||||||||||||||
Electrons per shell | 2, 8, 1 | |||||||||||||||||||||||||
Physical properties | ||||||||||||||||||||||||||
Phase at STP | solid | |||||||||||||||||||||||||
Melting point | 370.944 K (97.794 °C, 208.029 °F) | |||||||||||||||||||||||||
Boiling point | 1156.090 K (882.940 °C, 1621.292 °F) | |||||||||||||||||||||||||
Density (at 20° C) | 0.9688 g/cm3 | |||||||||||||||||||||||||
when liquid (at m.p.) | 0.927 g/cm3 | |||||||||||||||||||||||||
Critical point | 2573 K, 35 MPa (extrapolated) | |||||||||||||||||||||||||
Heat of fusion | 2.60 kJ/mol | |||||||||||||||||||||||||
Heat of vaporization | 97.42 kJ/mol | |||||||||||||||||||||||||
Molar heat capacity | 28.230 J/(mol·K) | |||||||||||||||||||||||||
Vapor pressure
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Atomic properties | ||||||||||||||||||||||||||
Oxidation states | −1, 0, +1 (a strongly basic oxide) | |||||||||||||||||||||||||
Electronegativity | Pauling scale: 0.93 | |||||||||||||||||||||||||
Ionization energies |
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Atomic radius | empirical: 186 pm | |||||||||||||||||||||||||
Covalent radius | 166±9 pm | |||||||||||||||||||||||||
Van der Waals radius | 227 pm | |||||||||||||||||||||||||
Spectral lines of sodium | ||||||||||||||||||||||||||
Other properties | ||||||||||||||||||||||||||
Natural occurrence | primordial | |||||||||||||||||||||||||
Crystal structure | body-centered cubic (bcc) (cI2) | |||||||||||||||||||||||||
Lattice constant | a = 428.74 pm (at 20 °C) | |||||||||||||||||||||||||
Thermal expansion | 69.91×10−6/K (at 20 °C) | |||||||||||||||||||||||||
Thermal conductivity | 142 W/(m⋅K) | |||||||||||||||||||||||||
Electrical resistivity | 47.7 nΩ⋅m (at 20 °C) | |||||||||||||||||||||||||
Magnetic ordering | paramagnetic | |||||||||||||||||||||||||
Molar magnetic susceptibility | +16.0×10−6 cm3/mol (298 K) | |||||||||||||||||||||||||
Young's modulus | 10 GPa | |||||||||||||||||||||||||
Shear modulus | 3.3 GPa | |||||||||||||||||||||||||
Bulk modulus | 6.3 GPa | |||||||||||||||||||||||||
Speed of sound thin rod | 3200 m/s (at 20 °C) | |||||||||||||||||||||||||
Mohs hardness | 0.5 | |||||||||||||||||||||||||
Brinell hardness | 0.69 MPa | |||||||||||||||||||||||||
CAS Number | 7440-23-5 | |||||||||||||||||||||||||
History | ||||||||||||||||||||||||||
Discovery and first isolation | Humphry Davy (1807) | |||||||||||||||||||||||||
Symbol | "Na": from New Latin natrium, coined from German Natron, 'natron' | |||||||||||||||||||||||||
Isotopes of sodium | ||||||||||||||||||||||||||
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Sodium was first isolated by Humphry Davy in 1807 by the electrolysis of sodium hydroxide. Among many other useful sodium compounds, sodium hydroxide (lye) is used in soap manufacture, and sodium chloride (edible salt) is a de-icing agent and a nutrient for animals including humans.
Sodium is an essential element for all animals and some plants. Sodium ions are the major cation in the extracellular fluid (ECF) and as such are the major contributor to the ECF osmotic pressure. Animal cells actively pump sodium ions out of the cells by means of the sodium–potassium pump, an enzyme complex embedded in the cell membrane, in order to maintain a roughly ten-times higher concentration of sodium ions outside the cell than inside. In nerve cells, the sudden flow of sodium ions into the cell through voltage-gated sodium channels enables transmission of a nerve impulse in a process called the action potential.