Nomenclature
CAS number: 7440-23-5
Natrium.
Description and references
Na; at. no. 11; at. wt 22.98976928; valence
1. Group IA (1). Alkali metal. Occurrence in earth's crust: 2.83%
by wt; principal cation in hydrosphere. Naturally occurring isotope:
23 (100%); radioactive isotopes (mass number): 19-22; 24-35. Prepd
by Davy in 1807 by electrolysis of fused sodium hydroxide. Found
in form of its compds, halides, silicates, carbonates; does not occur
free. Industrial prepns primarily in Downs cells, also in Castner
cells: Batsford, Chem. Metall. Eng. 26, 888, 932 (1932); Regelsberger, Chemische Technologie der Leichtmetalle Leipzig, 1926;
Hardie, Ind. Chem. 30, 161 (1954). Reviews: ACS Monograph
Series no. 133, entitled “Sodium,” M. Sittig,
Ed. (Reinhold, New York, 1956); Whaley, “Sodium, Potassium, Rubidium,
Cesium and Francium” in Comprehensive Inorganic
Chemistry Vol. 1, J. C. Bailar, Jr. et
al., Eds. (Pergamon Press, Oxford, 1973) pp 369-529; Chemistry of the Elements N. N. Greenwood,
A. Earnshaw, Eds. (Pergamon Press, New York, 1984) pp 75-116; C. H.
Lemke, V. H. Markant in Kirk-Othmer Encyclopedia
of Chemical Technology vol. 22 (Wiley-Interscience,
New York, 4th ed., 1997) pp 327-354.
Properties
Light, silvery-white metal; body-centered cubic
structure; lustrous when freshly cut; tarnishes on exposure to air,
becoming dull and gray. Soft at ordinary temp, fairly hard at -20°.
mp 97.82°; bp 881.4°; d20 0.968. Heat capacity
of solid: 0.292 cal/g deg; heat capacity of liquid at mp: 0.331
cal/g deg. Heat of fusion: 27.05 cal/g; thermal conductivity (cal/sec °C
cm): 0.205 (97.82°) 0.170 (400°). E0 (aqueous) Na/Na+ 2.714 V. Dangerous when wet. Violently decomposes water, forming sodium hydroxide and hydrogen
which may ignite spontaneously. Decomposes alc. Reacts vigorously
with oxygen, burning with a yellow flame. Emits characteristic yellow
color (589.2 nm) in flame. Combines directly with the halogens, with
phosphorus. Reduces most oxides to the elemental state, reduces metallic
chlorides. Dissolves in liquid ammonia to give a blue soln; when
heated in ammonia gas yields sodamide. Dissolves in mercury, forming
sodium amalgam. Keep under liquids contg no
oxygen, such as kerosene, naphtha.Caution
Direct contact with metal may be
corrosive and cause skin and eye burns. See: Fire Protection Guide to Hazardous Materials (National Fire Protection Assoc., Quincy, MA, 12th ed., 1997) Section
49, p 117.Use
Manuf of sodium compds, such as the cyanide, azide,
peroxide, etc.; manuf of tetraethyllead; manuf of refractory metals;
in org syntheses; for photoelectric cells; in sodium lamps; as catalyst
for many polymerization reactions. Alloyed with potassium in heat
transfer media. Prepn of alkoxide titrants.