Sodium is the chemical element with the symbol Na (from 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 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 and ECF compartment volume. Loss of water from the ECF compartment increases the sodium concentration, a condition called hypernatremia. Isotonic loss of water and sodium from the ECF compartment decreases the size of that compartment in a condition called ECF hypovolemia.

By means of the sodium-potassium pump, living human cells pump three sodium ions out of the cell in exchange for two potassium ions pumped in; comparing ion concentrations across the cell membrane, inside to outside, potassium measures about 40:1, and sodium, about 1:10. In nerve cells, the electrical charge across the cell membrane enables transmission of the nerve impulse—an action potential—when the charge is dissipated; sodium plays a key role in that activity.

© Wikipedia | CC-by-SA-3.0 | Read more …

Atomic properties

Standard atomic weight22.9897 ±2·10-8
Atomic mass22.9897 u

Atomic radii

Radius (empirical)180 pm
Radius (calculated)190 pm
Covalent radius166 ±9 pm
Van der Waals radius227 pm

Atomic shell

Electron configurationNe 3s1
Ionization energy(1st) 5.1390769 eV
(2nd) 47.28636 eV
(3rd) 71.62 eV
(4th) 98.936 eV
(5th) 138.404 eV
Shell model

Physical properties

Density0.968 g·cm−3 (293.1 K)
Molar volume2.378·10-5 m3·mol−1
Speed of sound3,200 m·s−1 (293.1 K)


Melting point370.9 K
Boiling point1,156 K
Liquid range785.1 K
Critical point(2,573 K @ 35 MPa)


Melting enthalpy2.6 kJ·mol-1
Enthalpy of vaporization97.7 kJ·mol-1
Binding energy107 kJ·mol-1

Heat and conductivity

Specific heat capacity1,230 J·kg−1·K−1
Thermal conductivity140 W·m-1·K-1
Expansion coefficient7.1·10-5 K-1
Work function2.75 eV


Mohs hardness0.5
Brinell hardness0.69 NM·m-2

Elastic properties

Young’s modulus10 GPa
Shear modulus3.3 GPa
Bulk modulus6.3 GPa

Electrical properties

Electrical conductivity2.1·107 S·m-1
Resistance4.9·10-8 Ωm


Magnetic susceptibility1.6·10-5 cm3·mol−1 (298 K)

Chemical properties

Basicitystrongly basic
Oxidation state1
Standard potential-2.713 V (Na+ + e- → Na)


Pauling scale0.93
Sanderson scale0.56
Allred-Rochow scale1.01
Mulliken scale0.91
Allen scale0.869
Ghosh-Gupta scale2.438 eV
Boyd-Edgecombe scale1
Nagle scale0.95
Pearson absolute negativity2.85 eV

Other properties

Natural occurrenceprimordial
Crystal structureBody-centered cubic
Goldschmidt Classificationlithophile
Superconductorwithout transition tempperature
Price/kg3 ±0.43 USD

Natural abundances

20,000 ppb ≈ 2.01·1014 M☉
40,000 ppb ≈ 7.95·1013 Mt
5.6·106 ppb ≈ 5.6 kg
Earth’s crust
2.3·107 ppb ≈ 6.37·108 Mt
1.105·107 ppb ≈ 15,100 Mt
Flowing water
8,000 ppb ≈ 128 Gt
Human body
1.4·106 ppb ≈ 98 g