Chemical elements
  Sodium
    Isotopes
    Energy
    Preparation
    Applications
    Physical Properties
      Sodium Ion
      Atomic Weight
    Chemical Properties
    PDB 131d-1bli
    PDB 1bph-1d10
    PDB 1d11-1ej2
    PDB 1eja-1gb5
    PDB 1gb6-1goh
    PDB 1gq2-1ikp
    PDB 1ikq-1jz1
    PDB 1jz2-1kvs
    PDB 1kvt-1me8
    PDB 1mg2-1nsz
    PDB 1nta-1oyt
    PDB 1p0s-1qjs
    PDB 1qnj-1s5d
    PDB 1s5e-1tjp
    PDB 1tk6-1uxt
    PDB 1uxu-1vzq
    PDB 1w15-1xc6
    PDB 1xcu-1yf1
    PDB 1ygg-1zko
    PDB 1zkp-2afh
    PDB 2agv-2bhc
    PDB 2bhp-2cc6
    PDB 2cc7-2dec
    PDB 2deg-2ein
    PDB 2eit-2fjb
    PDB 2fld-2gg8
    PDB 2gg9-2h9j
    PDB 2h9k-2ien
    PDB 2ieo-2jih
    PDB 2jin-2omd
    PDB 2omg-2p77
    PDB 2p78-2q68
    PDB 2q69-2qz7
    PDB 2qzi-2v35
    PDB 2v3h-2vwo
    PDB 2vx4-2wig
    PDB 2wij-2x1z
    PDB 2x20-2xmk
    PDB 2xmm-2zfq
    PDB 2zfr-3a6s
    PDB 3a6t-3b1e
    PDB 3b2n-3bos
    PDB 3bov-3ccr
    PDB 3ccs-3d7r
    PDB 3d97-3e3y
    PDB 3e40-3erp
    PDB 3euw-3fgw
    PDB 3fh4-3g3r
    PDB 3g3s-3gxw
    PDB 3gyz-3hwt
    PDB 3hww-3ijp
    PDB 3imm-3k0g
    PDB 3k13-3l7x
    PDB 3l88-3max
    PDB 3mbb-3mr1
    PDB 3mty-3nu3
    PDB 3nu4-3ot1
    PDB 3ow2-3qwc
    PDB 3qx5-3tfr
    PDB 3tfs-3v6o
    PDB 3v72-4ag2
    PDB 4aga-4eae
    PDB 4ecn-4g8t
    PDB 4gdt-8icw
    PDB 8icx-9icy

Physical Properties of Sodium






Sodium is a silver-white metal, rapidly tarnished by atmospheric oxidation, the process being attended by a greenish phosphorescence. In thin layers by transmitted light the metal has a brownish-yellow colour. The silver-white colour can be retained by distillation in a current of hydrogen, and preservation of the distillate in a sealed tube. Another method involves cleansing the surface with alcohol, and immersion of the bright metal in a saturated solution of naphthalene in light petroleum. Other protectors from oxidation are vaseline-oil, anhydrous ether, and petroleum freed from oxygen by distillation in hydrogen or carbon dioxide.

Sodium usually crystallizes in cubes, but it has also been obtained in quadratic octahedra. At - 20° C. it is hard, at 0° C. very ductile, at ordinary temperatures it can be moulded by the fingers, and at 50° C. it is soft. For its melting-point Rengade gives 97.90° C. Other values are: Regnault, Hagen, and Vicentini and Omodei, 97.6° C.; Kurnakoff and Pushin, Quercigh, and Guertler and Pirani, 97.5° C.; Masing and Tammann, 97° C.; and Holt and Sims, 92° C. The effect of pressure on the melting-point has been investigated by Tammann.

Several values are recorded for the boiling-point of sodium. Carnelley and Williams give values between 861° and 954° C.; Ruff and Johannsen give 877.5° C.; Hansen gives 742° C. at 760 mm. pressure and 418° C. at 0 mm. pressure; Perman gives 742° C. at 769.6 mm. pressure; and Krafft and Bergfeld give 140° C. in the vacuum of the cathode-light. In thin layers the vapour is colourless, but in thicker layers purple; at red heat it is yellow. The tension of the vapour varies between 1.2 mm. at 380° C. and 80 mm. at 570° C.; von Rechenberg found 1.94 mm. at 418° C. Its fluorescence has been studied by Dunoyer.

Attempts to determine the vapour density have been made by several experimenters, but the results have been unsatisfactory owing to the interaction of the vapour and the platinum, silver, iron, porcelain, or glass of the containing vessel.

The molecular weight was determined by Kraus to be 23 by dissolving the metal in liquid ammonia; other investigators give values for the molecular formula varying between Na0.5 and Na6.

The value of the specific heat at 0° C. is given by Griffiths as 0.2829. The specific heat from -185° to 20° C. is 0.2345, according to Nordmeyer and Bernoulli; from -34° to 7° C. Regnault gives 0.2943; from -79.5° to 17° C. Schiiz gives 0.2830; and from 0° to 157° C. Bernini gives values varying between 0.2970 and 0.333. For the specific heat of the solid at the melting-point, Rengade gives 0.3266. According to Iitaka, the specific heat of the solid is 0.330, and of the liquid 0.347, the corresponding values for the atomic heat being 7.59 and 7.98.

The latent heat of fusion per gram is, according to Joannis, 31.7 cal.; but Bernini gives 17.75 cal., and Rengade 27.23 cal.

Sodium is a good conductor of heat, and as a conductor of electricity it stands next to silver, copper, and gold. Its electric conductivity has been studied by several investigators.

The mean value of the density is 0.978. Gay-Lussac and Thenard give the density at 15° C. as 0.972 (water at 15° C.=1); Hackspill gives 0.9723 at 0° C.; Schroder 0.985 compared with water at 3.9° C.; Braumhauer 0.9735 at 13.5° C. and 0.9743 at 10° C. compared with water at the same temperatures; Vicentini and Omodei give 0.9519 for the solid at the melting-point and 0.9287 for the liquid; Ramsay 0.7414 for the liquid at the boiling-point; Dewar 0.9724 at 0° C. and 1.0066 at the temperature of liquid air (water at 0° C. =1); and Richards and Brink 0.9712 at 20° C.

The value last mentioned for the density gives 23.70 as the atomic volume. Vanstone found for the specific volume of the solid at 17° C. the value 1.0342; for the liquid at 110° C. 1.0794, and at 237° C. 1.1247.

According to Cohen and Wolff, sodium exists in two allotropic forms, designated α and β. The β-modification is slightly less dense than the α-form, and is produced by cooling the molten metal rapidly. At 97.22° C. it is transformed into the α-variety, the change having a measurable velocity, and being attended by the evolution of heat.


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