Science / Periodic Table of Elements / Sodium (Na): Atomic number: 11, Atomic mass: 22.98977 g.mol -1, Electronegativity: 0.9, Density: 0.97 g.cm -3 at 20 °C, Melting point: 97.5 °C, Boiling point: 883 °C, Vanderwaals radius: 0.196 nm, Ionic radius: 0.095 (+1) nm, Isotopes: 3, Electronic shell: [Ne] 3s1, Energy of first ionisation: 495.7 kJ.mol -1, Standard potential: - 2.71 V, Discovered by: Sir Humphrey Davy in 1807. Chemical element, symbol: Na, atomic number: 11 and atomic weight 22,9898. It’s a soft metal, reactive and with a low melting point, with a relative density of 0,97 at 20??C (68??F). From the commercial point of view, sodium is the most important of all the alkaline metals. Sodium reacts quickly with water, and also with snow and ice, to produce sodium hydroxide and hydrogen. When it’s exposed to air, metallic sodium recently cut looses its silvery appearance and acquires an opaque grey colour due to the formation of a sodium oxide coating. Sodium doesn’t react with nitrogen, not even at very high temperatures, but it can react with ammonia to form sodium amide. Sodium and hydrogen react above 200??C (390??F) to form sodium hydride. Sodium hardly reacts with carbon, but it does react with halogens. It also reacts with various metallic halides to form the metal and sodium chloride. Sodium doesn’t react with paraffinic hydrocarbons, but it forms addition compounds with naphthalene and other aromatic polycyclic compounds and with aryl alkenes. The reaction of sodium with alcohols is similar to the reaction of sodium with water, but slower. There are two general reactions with organic halides. One of them requires the condensation of two organic compounds, which form halogens when those are eliminated. The second type of reaction includes the replacement of halogen by sodium, to obtain a sodium organic compound. Applications: Sodium in its metallic form is very important in making esters and in the manufacture of organic compounds. Sodium is also a component of sodium chloride (NaCl) a very important compount found everywhere in the living environment. Other uses are: to improve the structure of certain alloys; in soap, in combination with fatty acids, in sodium vapor lamps, to descal metals, to purify molten metals. Solid sodium carbonate is needed to make glass. Sodium in the enviornment: Sodium is the sixth most abundant element in The Earth’s crust, which contains 2,83% of sodium in all its forms. Sodium is, after chloride, the second most abundant element dissolved in seawater. The most important sodium salts found in nature are sodium chloride (halite or rock salt), sodium carbonate (trona or soda), sodium borate (borax), sodium nitrate and sodium sulfate. Sodium salts are found in seawater (1.05%), salty lakes, alkaline lakes and mineral spring water. The production of salt is around 200 million tonnes per year; this huge amount is mainly extracted from salt deposits by pumping water down bore holes to dissolve it and pumping up brine. The sun and many other stars shine with visible light in which the yellow component dominates and this is given out by sodium atoms in a high-energy state.
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