From Wikipedia, the free encyclopedia
Jump to navigation Jump to search
Sodium,  11Na
Na (Sodium).jpg
General properties
Appearancesilvery white metallic
Standard atomic weight (Ar, standard)22.98976928(2)[1]
Sodium in the periodic table
Hydrogen Helium
Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon
Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon
Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton
Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon
Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon
Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson


Atomic number (Z)11
Groupgroup 1 (alkali metals)
Periodperiod 3
Element category  alkali metal
Electron configuration[Ne] 3s1
Electrons per shell
2, 8, 1
Physical properties
Phase at STPsolid
Melting point370.944 K ​(97.794 °C, ​208.029 °F)
Boiling point1156.090 K ​(882.940 °C, ​1621.292 °F)
Density (near r.t.)0.968 g/cm3
when liquid (at m.p.)0.927 g/cm3
Critical point2573 K, 35 MPa (extrapolated)
Heat of fusion2.60 kJ/mol
Heat of vaporization97.42 kJ/mol
Molar heat capacity28.230 J/(mol·K)
Vapor pressure
P (Pa) 1 10 100 1 k 10 k 100 k
at T (K) 554 617 697 802 946 1153
Atomic properties
Oxidation states−1, +1 (a strongly basic oxide)
ElectronegativityPauling scale: 0.93
Ionization energies
  • 1st: 495.8 kJ/mol
  • 2nd: 4562 kJ/mol
  • 3rd: 6910.3 kJ/mol
  • (more)
Atomic radiusempirical: 186 pm
Covalent radius166±9 pm
Van der Waals radius227 pm
Color lines in a spectral range
Spectral lines of sodium
Other properties
Natural occurrenceprimordial
Crystal structurebody-centered cubic (bcc)
Body-centered cubic crystal structure for sodium
Speed of sound thin rod3200 m/s (at 20 °C)
Thermal expansion71 µm/(m·K) (at 25 °C)
Thermal conductivity142 W/(m·K)
Electrical resistivity47.7 nΩ·m (at 20 °C)
Magnetic orderingparamagnetic[2]
Magnetic susceptibility+16.0·10−6 cm3/mol (298 K)[3]
Young's modulus10 GPa
Shear modulus3.3 GPa
Bulk modulus6.3 GPa
Mohs hardness0.5
Brinell hardness0.69 MPa
CAS Number7440-23-5
Discovery and first isolationHumphry Davy (1807)
Main isotopes of sodium
Iso­tope Abun­dance Half-life (t1/2) Decay mode Pro­duct
22Na trace 2.602 y β+ 22Ne
23Na 100% stable
24Na trace 14.96 h β 24Mg
| references
Sodium pellets in a container

Sodium (symbol Na, from the Latin name natrium) is the chemical element number 11 in the periodic table of elements. It follows that its nucleus includes 11 protons, and 11 electrons orbit around it (according to the simplified model known as "Niels Bohr atom"). Even if a large number of isotopes can be artificially made, all decay in a short time. As a result, all sodium found in nature (mainly in sea water) has the composition 11Na23, meaning that the nucleus includes 12 neutrons. The atomic mass of sodium is 22.9898; if it is rounded, it would be 23.

Properties[change | change source]

Sodium is a light, silver-coloured metal. Sodium is so soft that it can be easily cut with a knife. When it is cut, the surface will become white over time. This is because it reacts with air to form sodium hydroxide and sodium carbonate. Sodium is a little lighter than water; when it reacts with water it floats. This reaction is very fast. Hydrogen and sodium hydroxide are produced. The hydrogen may ignite. Since sodium melts at a low temperature, it melts when it reacts with water. It has one valence electron which is removed easily, making it highly reactive.

Compared with other alkali metals (metals in the first column of the periodic table), sodium is usually less reactive than potassium and more reactive than lithium.[4]

Chemical compounds[change | change source]

These are chemical compounds that contain sodium ions. Sodium only exists in 1 oxidation state: +1.

Discovery and name[change | change source]

Sodium was discovered by Sir Humphrey Davy, an English scientist, back in 1807. He made it by the electrolysis of sodium hydroxide. It is named after soda, a name for sodium hydroxide or sodium carbonate.

Use as element[change | change source]

It is used in the preparation of organic compounds. It is also used in the street lights that are orange, and ultra violet lights.

Use as compounds[change | change source]

Sodium compounds are used in soaps, toothpaste, baking and antiacids. .

Occurrence and production[change | change source]

Sodium does not exist as an element in nature; its easily removed valence electron is too reactive. It exists as an ion in chemical compounds. Sodium ions are found in the ocean. It is also found as sodium chloride in the earth's crust, where it is mined.

Sodium is normally made by electrolysis of very hot sodium chloride that was melted.

Use in organisms[change | change source]

Sodium ion in the form of sodium chloride is needed in the human body, but large amounts of it cause problems, which is why one should not eat too much salt and other food items with huge sodium amount (such as biscuits with baking soda). Many organisms in the ocean depend on the proper concentration of ions in sea water to live.

Related pages[change | change source]

References[change | change source]

  1. Meija, J.; Coplen, T. B.; Berglund, M.; Brand, W.A.; De Bièvre, P.; Gröning, M.; Holden, N.E.; Irrgeher, J. et al. (2016). "Atomic weights of the elements 2013 (IUPAC Technical Report)". Pure and Applied Chemistry 88 (3): 265-91. doi:10.1515/pac-2015-0305. 
  2. Magnetic susceptibility of the elements and inorganic compounds, in Lide, D. R., ed. (2005). CRC Handbook of Chemistry and Physics (86th ed.). Boca Raton (FL): CRC Press. ISBN 0-8493-0486-5.
  3. Weast, Robert (1984). CRC, Handbook of Chemistry and Physics. Boca Raton, Florida: Chemical Rubber Company Publishing. pp. E110. ISBN 0-8493-0464-4.
  4. De Leon, N. "Reactivity of Alkali Metals". Indiana University Northwest. Retrieved 2007-12-07.