Na
Sodium

atomic no. 11, atomic wt. 22.997, metal, row 4, col. 1A, val. 1, orbits 2-8-1


{Merck Index - © 1952 by Merck & Co., Inc.}

Sodium. Natrium. Na; at. wt. 22.997; at. no. 11; valence 1. Prepd. by Davy in 1807 by electrolysis of fused sodium hydroxide. Found in form of its compounds, halides, silicates, carbonates; does not occur free; constitutes 2.83% of the crust of the earth. Prepn.: Batsford, Chem. Met. Eng. 26, 888, 932 (1932); Regelsberger, Chemische Technologic der Leichtmetalle, Leipzig, 1926; U.S. pat. 2,391,728 (McConica, MacPhail, Kirk to Dow Chemical Co., 1945).

Light, silvery-white metal; body-centered cubic structure; lustrous when freshly cut; tarnishes on exposure to air, becoming dull and gray. Soft at ordinary temperature, fairly hard at –20°. d. 0.97; m. 97.7° ± 0.2°; b. 883°. Violently decomposes water, forming sodium hydroxide and hydrogen which may ignite spontaneously. Decomposes alcohol.

Reacts vigorously with oxygen, burning with a yellow 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 solution; when heated in ammonia gas yields sodatnide. Dissolves in mercury, forming sodium amalgam.

Keep under liquids contg. no oxygen, such as kerosene, naphtha.

Use: Manuf. of sodium compounds, such as the cyanide, azide, peroxide, etc.; in manuf. of lead tetraethyl; in org. syntheses; for photoelectric cells; in sodium lamps.

Toxicity: Extremely caustic to all tissue.

{Mineral Deficiencies in Plants}

As sodium is not strictly an essential element it cannot be expected to have a specific role in the metabolic activities of plants.

Where sodium produces significant effects it is often regarded as a conserver of potassium and as being able partly to replace that element in its role. In no instance, however, has it been shown that sodium can wholly replace potassium where the latter is acutely deficient. In such circumstances, sodium is ineffective as a substitute for potassium, even for sodium-loving plants such as sugar beet, mangold and barley. Sodium seems to affect the water relations of plants and often enables sugar beet and other crops to withstand drought conditions which would otherwise produce severe adverse effects.


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