Atomistry » Sodium
Atomistry »
  Sodium »
    Isotopes »
    Energy »
    Preparation »
    Applications »
    Physical Properties »
    Chemical Properties »
    PDB 131d-1b7r »
    PDB 1b7s-1c82 »
    PDB 1c8v-1de7 »
    PDB 1det-1ev6 »
    PDB 1evr-1gb5 »
    PDB 1gb6-1ghx »
    PDB 1ghy-1hn1 »
    PDB 1hnf-1jay »
    PDB 1jb7-1k73 »
    PDB 1k7e-1l0i »
    PDB 1l0r-1m65 »
    PDB 1m90-1nji »
    PDB 1nnh-1oan »
    PDB 1oar-1ph6 »
    PDB 1ph7-1qsx »
    PDB 1qtk-1s3x »
    PDB 1s45-1t3p »
    PDB 1t4b-1u8r »
    PDB 1ubs-1v54 »
    PDB 1v55-1w4n »
    PDB 1w5n-1x7d »
    PDB 1x9j-1y4d »
    PDB 1y5y-1z1q »
    PDB 1z2u-1zud »
    PDB 1zum-2aoc »
    PDB 2aoe-2bhp »
    PDB 2bii-2c8x »
    PDB 2c8y-2cn0 »
    PDB 2czs-2e4r »
    PDB 2e54-2eka »
    PDB 2ekb-2fm1 »
    PDB 2fmp-2gg2 »
    PDB 2gg3-2gu7 »
    PDB 2gum-2hti »
    PDB 2htx-2isp »
    PDB 2isz-2jln »
    PDB 2mat-2oj0 »
    PDB 2ok7-2ozt »
    PDB 2p0o-2plo »
    PDB 2ply-2qd6 »
    PDB 2qd8-2r22 »
    PDB 2r25-2uyz »
    PDB 2uzz-2vrp »
    PDB 2vrr-2wcp »
    PDB 2wd0-2wof »
    PDB 2woi-2x2v »
    PDB 2x5x-2xjq »
    PDB 2xjr-2xzi »
    PDB 2xzj-2yeq »
    PDB 2yfa-2zgb »
    PDB 2zgx-3a03 »
    PDB 3a07-3ahi »
    PDB 3ajn-3b1q »
    PDB 3b2n-3biu »
    PDB 3bjp-3c7h »
    PDB 3c7o-3cpw »
    PDB 3cq8-3dfh »
    PDB 3dh4-3e3y »
    PDB 3e40-3ept »
    PDB 3epz-3f9l »
    PDB 3fak-3fvi »
    PDB 3fvs-3gdg »
    PDB 3gdx-3h09 »
    PDB 3h0n-3hwd »
    PDB 3hwe-3ic9 »
    PDB 3icf-3ivu »
    PDB 3iwf-3k93 »
    PDB 3k9g-3la1 »
    PDB 3lbg-3m9y »
    PDB 3ma9-3mo9 »
    PDB 3moc-3n0p »
    PDB 3n0u-3nrv »
    PDB 3nte-3off »
    PDB 3ogc-3p1l »
    PDB 3p2y-3pkh »
    PDB 3pkk-3pzs »
    PDB 3q11-3qpz »
    PDB 3qq0-3r57 »
    PDB 3r9b-3rn1 »
    PDB 3rnx-3si4 »
    PDB 3sib-3t09 »
    PDB 3t0a-3tjl »
    PDB 3tkj-3tzl »
    PDB 3u0a-3upw »
    PDB 3uq0-3v3r »
    PDB 3v45-3vi2 »
    PDB 3vif-3way »
    PDB 3wc3-3wxo »
    PDB 3wxt-3zu5 »
    PDB 3zux-4adj »
    PDB 4adn-4b16 »
    PDB 4b1a-4bkr »
    PDB 4blw-4c44 »
    PDB 4c6s-4cnt »
    PDB 4coo-4ddo »
    PDB 4def-4dxz »
    PDB 4dy7-4egs »
    PDB 4ehu-4f5q »
    PDB 4f5r-4foi »
    PDB 4fpa-4ge8 »
    PDB 4gfi-4gwn »
    PDB 4gxi-4hfb »
    PDB 4hfc-4hxv »
    PDB 4i05-4ii8 »
    PDB 4iib-4j07 »
    PDB 4j0n-4jdo »
    PDB 4jer-4jtj »
    PDB 4jtk-4khq »
    PDB 4khs-4kxw »
    PDB 4kxx-4lg8 »
    PDB 4lgd-4lzd »
    PDB 4lzg-4mf2 »
    PDB 4mf8-4mye »
    PDB 4myq-4nij »
    PDB 4njh-4nw8 »
    PDB 4nw9-4o9m »
    PDB 4oa8-4ovz »
    PDB 4owb-4pcg »
    PDB 4pd5-4poc »
    PDB 4pod-4q39 »
    PDB 4q3a-4qm6 »
    PDB 4qnk-4r1m »
    PDB 4r33-4rk5 »
    PDB 4rko-4tls »
    PDB 4tm6-4u99 »
    PDB 4u9g-4us4 »
    PDB 4us5-4w94 »
    PDB 4w96-4wxb »
    PDB 4wxg-4xd1 »
    PDB 4xda-4xmx »
    PDB 4xmy-4xr6 »
    PDB 4xr9-4yhf »
    PDB 4yhq-4z2i »
    PDB 4z3u-4zke »
    PDB 4zky-5ab3 »
    PDB 5abd-5azp »
    PDB 5b05-5bom »
    PDB 5bpc-5cb6 »
    PDB 5ccb-5cvp »
    PDB 5cvy-5dba »
    PDB 5dbb-5dwk »
    PDB 5dwz-5ekj »
    PDB 5ekm-5ez4 »
    PDB 5ezb-5fht »
    PDB 5fhy-5g3b »
    PDB 5g3c-5gtl »
    PDB 5gu8-5hl0 »
    PDB 5hlk-5i8f »
    PDB 5i8g-5imc »
    PDB 5imd-5j28 »
    PDB 5j29-5ji5 »
    PDB 5jid-5k8r »
    PDB 5k9h-5ku9 »
    PDB 5kvc-5l4i »
    PDB 5l4j-5llm »
    PDB 5llu-5m0e »
    PDB 5m0m-5mdu »
    PDB 5meh-5moz »
    PDB 5mqr-5n9f »
    PDB 5n9g-5nmn »
    PDB 5nns-5o6x »
    PDB 5o6y-5ome »
    PDB 5omi-5pof »
    PDB 5pog-5ppj »
    PDB 5ppk-5pqn »
    PDB 5pqo-5pru »
    PDB 5prv-5psy »
    PDB 5psz-5pu5 »
    PDB 5pu6-5pv9 »
    PDB 5pva-5qte »
    PDB 5qtf-5rdb »
    PDB 5rdc-5syk »
    PDB 5syl-5tcd »
    PDB 5tde-5txi »
    PDB 5txq-5u4u »
    PDB 5u63-5uj6 »
    PDB 5uju-5v0c »
    PDB 5v0d-5vb7 »
    PDB 5vb8-5vwn »
    PDB 5vxa-5wiv »
    PDB 5wjo-5x2p »
    PDB 5x2q-5xuu »
    PDB 5xuz-5yr7 »
    PDB 5ysu-5znq »
    PDB 5zo8-5zu6 »
    PDB 5zwy-6agr »
    PDB 6ah7-6awx »
    PDB 6awy-6bfk »
    PDB 6bfo-6c02 »
    PDB 6c0l-6cgf »
    PDB 6chk-6ctm »
    PDB 6ctn-6d2s »
    PDB 6d4o-6dmd »
    PDB 6dmi-6e8s »
    PDB 6e8t-6eqe »
    PDB 6eqv-6f1h »
    PDB 6f1p-6flu »
    PDB 6fmp-6g3e »
    PDB 6g3o-6gn6 »
    PDB 6gn7-6h6l »
    PDB 6h6m-6hip »
    PDB 6hj3-6hyz »
    PDB 6hz0-6iam »
    PDB 6ibl-6jb8 »
    PDB 6jbc-6k8g »
    PDB 6k96-6leh »
    PDB 6lfh-6mbq »
    PDB 6mc0-6myi »
    PDB 6myj-6ne6 »
    PDB 6nfp-6nxs »
    PDB 6nxx-6ont »
    PDB 6oog-6p8k »
    PDB 6p8l-6pui »
    PDB 6puj-6qci »
    PDB 6qck-6qsk »
    PDB 6qsr-6r7a »
    PDB 6r7j-6rj4 »
    PDB 6rjb-6rz4 »
    PDB 6rz5-6sec »
    PDB 6sed-6sxc »
    PDB 6sxe-6tbi »
    PDB 6tbj-6to7 »
    PDB 6tod-6u3a »
    PDB 6u66-6uy9 »
    PDB 6uzm-6vf2 »
    PDB 6vf3-6vxv »
    PDB 6vyd-6wk2 »
    PDB 6wkq-6x5w »
    PDB 6x9h-6xwm »
    PDB 6xxq-6yc2 »
    PDB 6yc3-6yq1 »
    PDB 6yqq-6z5e »
    PDB 6z5t-6zjr »
    PDB 6zjs-7a20 »
    PDB 7a2j-7ala »
    PDB 7am5-7baz »
    PDB 7bb1-7bvq »
    PDB 7bvw-7cm8 »
    PDB 7cmz-7dct »
    PDB 7dcu-7f35 »
    PDB 7f6s-7jr8 »
    PDB 7jsj-7kkg »
    PDB 7kkr-7l00 »
    PDB 7l03-7lqy »
    PDB 7lqz-7mij »
    PDB 7mik-7neu »
    PDB 7nf5-7p2h »
    PDB 7p2j-7s7w »
    PDB 7s86-9ici »
    PDB 9icj-9icy »

Element Sodium Na, Alkali Metal

About Sodium

The chemical relations of sodium are very similar to those of potassium, so that for chemical purposes the one metal can in most cases replace the other. This holds good especially for those reactions in which the ions come into account. The reason of this is that natrion also represents a far more stable state than metallic sodium, and the reactions of this element, as in the case of potassium, are therefore chiefly characterised by the fact that the ion is formed with especial readiness from the metal, but the metal only with difficulty from the ion. Since, further, the state of the salts in the solid form approaches more nearly to that of the ions than to that of the metal, sodium, like potassium, will be easily transformed from one of its salts into another, but will be converted only with difficulty from a salt into the metal or a compound closely related to this.

Metallic sodium does not occur in nature, since it would everywhere have an opportunity of exercising its tendency to pass into natrion. Natrion, however, has an extensive distribution, and, along with chloridion, with which it occurs in sea-water, it may be regarded as the most abundant ion in those parts of the earth's surface which are accessible to us.

In more remote times, the compounds of the two elements potassium and sodium were confused with one another. When it was learned how to distinguish them, caustic potash was known as the vegetable, and caustic soda as the mineral alkali, because the former was obtained chiefly from the ash of plants, the latter from common salt. It was later found by Klaproth that both elements are present in the mineral kingdom. So far as the vegetable kingdom is concerned, an essential difference does certainly exist between the two elements, for compounds of potassium must be present in considerable amount in plants in order that these may develop normally. Sodium compounds, it is true, are never wanting in plants, but they are more chance constituents which pass into the plants from the soil, in which they are always present, and seem not to play any particular part in them.

Although, therefore, normal vegetation may be hindered by an entire exclusion of sodium compounds (although no indubitable evidence on this point exists), it is certain that the quantities of sodium which may possibly be necessary for a plant are incomparably smaller than the amounts of potassium which are indispensable.

The cause of this difference may be found in the following circumstance. Whereas the soil in which plants thrive has the remarkable property of withdrawing dissolved potassium compounds from solution, and retaining them in such a way that they can be taken up only in a very slight degree by water, the behaviour is quite different with respect to the sodium compounds. These are not retained by the soil, but filter through without difficulty. Whereas, therefore, the amount of potassium compounds in the soil is considerable and almost independent of chance conditions, the amount of the sodium compounds is subject to variation and to chance. On the principle of the survival of the fittest, it is intelligible that the chemical requirements of the plants, the satisfaction of which is effected by an alkali metal (or its ion), should be supplied by the constantly present potassium, since organisms whose life depended on utilising sodium compounds would die out by reason of the readily occurring lack of these.

The accumulation of natrion in sea-water is due to the same cause. When in the decomposition of the rocks by water and carbonic acid, the alkali metals pass into solution in the form of their ions, they follow, in the first instance, the general movement of the water towards the ocean. The potassium, however, is mostly retained on the way, because it is seized hold of by the soil; the sodium, however, passes on unhindered to the sea, and is deposited again in the solid form only in rare cases, viz. when the sea-water is concentrated by evaporation until the solid salt forms.

Cases of this have occurred, especially in former geological periods, and have given rise to beds of rock-salt or sodium chloride, the two ions which are present in greatest abundance in sea-water having been deposited together as solid salt.

Metallic Sodium

We have already, on several occasions, become acquainted with metallic sodium as a silver white, soft, and readily fusible metal, which reacts energetically in contact with water, and just as readily forms compounds with many other substances. It behaves, in general, quite similarly to potassium, from which it is distinguished by the somewhat inferior violence of its reactions.

Thus, sodium does not take fire when thrown on water; it does so, however, if its motion and the cooling which is thereby effected is prevented. This happens when the metal is placed on wet paper or on an aqueous jelly of glue or of starch. The evolved hydrogen as well as a portion of the metal then burns with a bright yellow flame, and all the flames in a room in which such a combustion has occurred burn distinctly yellow for a considerable time. This is due to the fact that the dissipated sodium compounds colour the flames yellow, even when present in the minutest quantities.

Sodium melts at 97.5°, and boils at about 740°. The accurate determination of its vapour density is difficult, but the experiments which have been made agree in showing that the molar weight of sodium vapour is 23, or equal to the combining weight. This identity is a general property of the metals, so far as these are known in the vapour form, and less doubtful cases of the confirmation of this rule will be given later.

By mixture with other metals, the melting point of sodium is lowered. This is especially well seen on adding potassium; in this way alloys can easily be obtained which are liquid at the room temperature.

This phenomenon is by no means to be explained as a consequence of chemical combination between the metals; on the contrary, it is the simple consequence of the perfectly general fact that the melting point of every substance is lowered by the addition of such substances as are soluble in the liquid form of the first substance. If the melting point of the pure substance is not too high above room temperature, it may be lowered to below this temperature, and the phenomenon in question makes its appearance.

The first preparation of metallic sodium was effected by Davy by means of the voltaic pile at the same time as that of potassium. Shortly afterwards the method of obtaining it by distillation of sodium carbonate with charcoal was discovered, corresponding to the method mentioned under potassium. Since about 1860, sodium has been obtained on the large scale by this method, the metal being used for preparing aluminium. Recently, however, the electrical method has again been adopted, and sodium is obtained by the decomposition of sodium hydroxide by means of the electric current. By reason of the comparatively small cost of electrical energy, combined with the good yield obtained, sodium can be obtained more cheaply by this than by the old method. It is remarkable that this method is identical with that by which sodium was first prepared, for on that occasion also, sodium hydroxide was the original substance.

The electrolysis is carried out in iron pots divided by permeable partitions. At the anode oxygen escapes, at the cathode sodium and hydrogen are formed. The separated metal is lighter than the liquid hydroxide, and therefore floats to the surface; it is skimmed off from time to time.

Sodium can also be obtained by the electrolysis of fused sodium chloride. Much difficulty, however, is caused by the high melting point of this salt. The melting point can be lowered by mixing it with potassium chloride; mixtures of sodium with a little potassium are then obtained, but not the pure metal. For this reason, successful attempts have also been made to employ the readily fusible sodium nitrate for the electrolysis.

Metallic sodium is largely used in the arts and in the laboratory. Its former importance for obtaining other difficultly reducible metals has been lost, since the object can generally be attained more readily by means of magnesium or aluminium, or by the electrolytic method. It is used, however, as a powerful reducing agent in many reactions in organic chemistry, and for obtaining reactive intermediate products.

For these purposes, the metal is best employed in a condition in which it offers a large surface. Since, on account of the softness of the metal, it cannot be reduced to small pieces by blows or by filing, it is forced, by means of an iron screw press, through narrow openings, and is thus obtained in the form of wire or of ribbon, according to the shape of the opening. Since in this state the metal very rapidly oxidises in the air, the wire is allowed to fall directly into the liquid on which it is to act, or it is collected in a liquid which does not contain oxygen. Petroleum, which is usually employed for this purpose, has the disadvantage that it is difficult to remove; for chemical purposes, therefore, it is better to use readily volatile hydrocarbons obtained from the low-boiling portions of petroleum (so-called petroleum benzine or petroleum ether).

Sodium Occurrence

Although sodium in the free state is not found in nature, it is present in combination in most minerals. Soda-felspar or albite is a double silicate of sodium and aluminium, 3Na2O,Al2O3,6SiO2. Sea-water contains 2.6 to 2.9 per cent, of sodium chloride, NaCl, the deposits left by the evaporation of inland seas being known as rock-salt Both the carbonates and the sulphate of sodium occur dissolved in the water of many mineral springs, while the sulphate is a constituent of certain double salts, such as glauberite or sodium calcium sulphate, and blodite or sodium magnesium sulphate. Great deposits of Chile saltpetre or sodium nitrate, NaNO3, are present in Chile. Cryolite or sodium aluminium fluoride, 3NaF,AlF3, is an important mineral found in Greenland. Sodium carbonate occurs in South America and Egypt, and is also found as gaylussite, a double carbonate of sodium and calcium. Tincal or disodium tetraborate, Na2B4O7,10H2O, is native to Thibet, India, and California, and a double borate of sodium and calcium called cryptomorphite is also found.

Sodium History

The knowledge of sodium carbonate or "soda" is of great antiquity, as indicated by two references in the Bible. The word translated " nitre " in the Authorized Version means " natron " or " soda," and is correctly rendered "lye" in Jer. II. 22 in the Revised Version. No alteration has been made in the other reference. The confusion of terms evidently originated in the resemblance between the Greek vcrpov employed by Dioscorides and the Latin nitrum used by Pliny to denote sodium carbonate, and the word " nitre," loosely employed in early English as synonymous with "natron" or "soda," but now reserved for potassium nitrate.

In the sixteenth century Biringuccio seems to have appreciated the distinction between "nitrum" or soda and "sal nitri" or saltpetre. Somewhat earlier the Arabs introduced into Europe the words "natrun," "natrum," and "natron," signifying soda, and " nitrum," meaning saltpetre. They also introduced the word "alkali", but drew no distinction between soda, derived from the ashes of sea-plants, and potash, obtained from the ashes of land-plants. These substances were denominated " fixed alkali" in contradistinction to the volatile ammonium carbonate.

In 1736 Duhamel de Monceau noted the difference between the "mineral alkali" or soda obtained from rock-salt and the "vegetable alkali" or potash extracted from plant-ashes. Marggraf recorded the difference in flame-coloration produced by the two substances, and in 1796 Klaproth discovered the presence of "vegetable alkali" in the mineral world as leucite. At an earlier date it was noticed that the so-called "mild alkali" or sodium carbonate is converted into "caustic alkali," or sodium hydroxide (in modern parlance), by the action of slaked lime, and in 1756 Black proved the presence of "fixed air" (carbon dioxide) in the "mild alkali."

In 1807 Davy isolated the alkali-metals by electrolysis of the fused hydroxides, thus proving the invalidity of Lavoisier's conception of the oxides as elementary substances.


Last articles

Zn in 7VD8
Zn in 7V1R
Zn in 7V1Q
Zn in 7VPF
Zn in 7T85
Zn in 7T5F
Zn in 7NF9
Zn in 7M4M
Zn in 7M4O
Zn in 7M4N
© Copyright 2008-2020 by
Home   |    Site Map   |    Copyright   |    Contact us   |    Privacy