Chemical elements
  Magnesium
    Isotopes
    Energy
    Preparation
    Physical Properties
    Chemical Properties
    PDB 101d-1atr
    PDB 1ats-1bup
    PDB 1bvw-1cp8
    PDB 1cqi-1d9d
    PDB 1d9z-1dxe
    PDB 1dxf-1ed9
    PDB 1edr-1f2u
    PDB 1f3f-1fmw
    PDB 1fnm-1g8n
    PDB 1g8t-1gtv
    PDB 1gua-1hnz
    PDB 1hpm-1i95
    PDB 1i96-1iv2
    PDB 1iv3-1jgy
    PDB 1jgz-1k01
    PDB 1k02-1kil
    PDB 1kiz-1l3p
    PDB 1l3r-1lvh
    PDB 1lvk-1mn9
    PDB 1mnd-1n33
    PDB 1n52-1ngg
    PDB 1ngj-1ntb
    PDB 1nu4-1o93
    PDB 1o9t-1ouo
    PDB 1ouq-1pg4
    PDB 1php-1q54
    PDB 1q5h-1qgx
    PDB 1qh1-1r4a
    PDB 1r4x-1rqy
    PDB 1rrf-1s9j
    PDB 1sa0-1svm
    PDB 1svs-1te6
    PDB 1tez-1u0c
    PDB 1u0h-1uhx
    PDB 1uik-1vc9
    PDB 1vcl-1vsd
    PDB 1vst-1wax
    PDB 1wb1-1wzn
    PDB 1x06-1xg4
    PDB 1xhf-1xqa
    PDB 1xr1-1y84
    PDB 1y8a-1yns
    PDB 1yq2-1z0a
    PDB 1z0d-1zc4
    PDB 1zca-1zvq
    PDB 1zvw-2a5l
    PDB 2a5y-2anr
    PDB 2anv-2b8q
    PDB 2b8r-2bku
    PDB 2bm0-2c18
    PDB 2c19-2cic
    PDB 2cie-2d0q
    PDB 2d1k-2dw6
    PDB 2dw7-2egh
    PDB 2eh3-2f6t
    PDB 2f6v-2fmh
    PDB 2fmk-2g3h
    PDB 2g3s-2gl5
    PDB 2gl6-2h7v
    PDB 2h7x-2hne
    PDB 2hny-2i34
    PDB 2i3d-2io7
    PDB 2io8-2j3e
    PDB 2j3q-2jg1
    PDB 2jg2-2nvu
    PDB 2nvx-2oem
    PDB 2ofw-2our
    PDB 2ous-2pcl
    PDB 2pda-2px3
    PDB 2pxi-2q5z
    PDB 2q66-2qlx
    PDB 2qm1-2qwy
    PDB 2qx0-2rdr
    PDB 2rds-2uxq
    PDB 2uxr-2vbn
    PDB 2vbu-2vk8
    PDB 2vkf-2w7x
    PDB 2w83-2wi3
    PDB 2wia-2wzd
    PDB 2wzg-2xcp
    PDB 2xdg-2y0s
    PDB 2y3p-2z4r
    PDB 2z4s-2zjy
    PDB 2zkj-301d
    PDB 302d-3a5k
    PDB 3a5l-3ak8
    PDB 3ak9-3bb3
    PDB 3bb4-3bsu
    PDB 3btx-3c95
    PDB 3c9h-3ckg
    PDB 3clc-3cxc
    PDB 3cxo-3der
    PDB 3des-3du3
    PDB 3du7-3e84
    PDB 3e8m-3eni
    PDB 3eno-3ezw
    PDB 3ezx-3fcs
    PDB 3fct-3fqr
    PDB 3fqt-3g3y
    PDB 3g45-3gj3
    PDB 3gj4-3gve
    PDB 3gvn-3hdz
    PDB 3hfw-3hrz
    PDB 3hs0-3hzt
    PDB 3hzv-3iaf
    PDB 3iak-3ilo
    PDB 3imd-3jvt
    PDB 3jvv-3ka6
    PDB 3ka8-3kkp
    PDB 3kkq-3kxi
    PDB 3kxo-3ldw
    PDB 3lee-3lwm
    PDB 3lwn-3mey
    PDB 3mf4-3n23
    PDB 3n2a-3nkv
    PDB 3nl3-3ocm
    PDB 3ocu-3oiu
    PDB 3oiv-3oye
    PDB 3oyf-3pu9
    PDB 3pwx-3rmj
    PDB 3ro8-3t3p
    PDB 3t5t-3ukd
    PDB 3umm-3v9w
    PDB 3v9x-412d
    PDB 421p-4aov
    PDB 4ap5-4dg1
    PDB 4dh1-4dug
    PDB 4dwd-4en4
    PDB 4en5-4fk1
    PDB 4fkx-8ici
    PDB 8ruc-9rub

Element Magnesium, Be, Alkaline Earth Metal





About Magnesium

Magnesium bears the same relation to calcium as sodium does to potassium. This relation finds expression not only in the values of the combining weights, but also in the similarities to the other members of the group. This is particularly well seen in the fact that magnesium is of more frequent occurrence than calcium, and that, in its properties, it differs from calcium more than the latter does from the corresponding elements of higher combining weight, strontium and barium.

That an elementary metal is present in the magnesium salt, was regarded by Davy as indubitable from the time that the corresponding fact was recognised in the case of potassium and sodium. Bunsen, however, was the first to prepare the metal itself. He obtained it by the electrolysis of the fused chloride.

The electrolysis can be performed in the lecture by employing fused carnallite as electrolyte. The partition and the prolongation of the crucible are of asbestos mill-board, the cathode is a piece of iron wire, and the anode a thin arc-carbon. The strength of the current is about 3-10 amperes.

Magnesium is now manufactured in very large amount by electrolysis, and is used for various purposes. It is a white, rather tough metal, which keeps fairly well in the air; it is scarcely attacked by cold water, but in boiling water it slowly evolves hydrogen. In dilute acids it very rapidly dissolves, with energetic evolution of hydrogen. It melts at about 750°, and volatilises at a bright white heat.

Heated in the air, magnesium burns with a very bright, white flame, which is largely made use of. For example, instantaneous photographs can be easily taken by magnesium light. For this purpose magnesium is used in powder form, and is either blown through a flame or is mixed with potassium chlorate or perchlorate, sometimes with potassium permanganate, and ignited.

The former method has the advantage that comparatively little metal is required, especially when pure oxygen is used instead of air for blowing it; but it has the disadvantage that the flash lasts for a comparatively long time, about 0.3 second. The second method requires larger quantities of magnesium, but the flash lasts only 0.1 second, or less. The last-mentioned mixture, however, is rather dangerous, as it readily explodes; it ought not, therefore, to be prepared in large quantity.

Magnesium is also used for other purposes where a bright, transient light is required; in such cases the magnesium is generally burned in the form of ribbon in specially constructed lamps. Magnesium is also used for adding to fireworks.

Magnesium is an exceedingly effective reducing agent at a high temperature. Silicon, boron, and most of the other metals can be obtained by heating their oxygen compounds with magnesium powder, the latter thereby passing into its oxide, MgO.


Occurrence of Magnesium

Meteorites, which are samples of extra-terrestrial origin, often contain combined magnesium. It is, after iron, their most important metallic constituent. Magnesium has been spectroscopically discovered in the sun, and in the earth's crust the number of its atoms has been estimated as 1.67 per cent, of the total of elementary atoms.

Magnesium compounds are widely distributed over the earth. Magnesium chloride, MgCl2, and, to a lesser extent, magnesium bromide, MgBr2, and magnesium iodide, MgI2, occur in natural waters - including sea-water. The slightly soluble magnesium fluoride, MgF2, occurs as the mineral sellaite. Sea-water and most mineral springs contain more salts of magnesium than of calcium, but in river-water calcium salts preponderate. Magnesium sulphate is a prevalent magnesium salt in natural water, and Epsom salts, MgSO4.7H2O, derive their name from their occurrence in the famous mineral spring at Epsom. MgSO4.7H2O occurs as the mineral epsomite or, as it is called when found in the Stassfurt deposits, reichardtite.

The Stassfurt deposits had a marine origin, and consist of narrow bands of anhydrous calcium sulphate, interspersed, at fairly regular intervals, through a mass of rock salt. Beds rich in magnesium and potassium salts cap the narrow seams of calcium sulphate. The deposits divide roughly into four regions -

  1. Anhydrite, CaSO4.
  2. Polyhalite, 2CaSO4.MgSO4.KSO4.2H2O, about 60 metres.
  3. Kieserite, MgSO4.H2O, about 30 metres.
  4. Carnallite, MgCl2.KCl4.6H2O, about 23 metres.


These deposits are the most important commercial source of magnesium and its salts. They contain also the following salts - tachhydrite, CaCl2.2MgCl2.12H2O, krugite, KSO4.4CaSO4.MgSO4.2H2O, bischoffite, MgCl2.6H2O, kainite, KCl.MgSO4.3H2O, schonite or picromerite, KSO4.MgSO4.6H2O, leonite, KSO4.MgSO4.4H2O, langbeinite, KSO4.2MgSO4, blodite or astrakanite, Na2SO4.MgSO4.4H2O, loewite, Na2SO4.MgSO4.2H2O, and vanthoffite, 3Na2SO4.MgSO4.

The double sulphate, (NH4)2SO4.MgSO4.6H2O, occurs as boussingaultite.

Many natural waters contain magnesium bicarbonate, Mg(HCO3)2; normal carbonates are represented in many mineral species. MgCO3 occurs as magnesite; breunnerite, (Mg,Fe)CO3, occurs in meteorites. Nesquehonite is MgCO3.3H2O, and dolomite, (Ca,Mg)CO3, is widely distributed. Many mountain ranges consist largely of this important mineral species. Ankerite is (Mg,Fe)CO3.CaCO3.

Basic carbonates occur as hydromagnesite, 3MgCO3.Mg(OH)2.3H2O, landsfordite, 4MgO.3CO2.22H2O, and hydrogioberite, [(Mg.OH).CO3.2H2O].

Northupite is Na2CO3.MgCO3.NaCl.

Magnesium oxide, MgO, occurs as periclase and, hydrated, in brucite, Mg(OH)2. In conjunction with other oxides it occurs as magnoferrite, MgO.Fe2O3, and jacobsite, (Mn,Mg)O.(Fe,Mn)2O3.

Magnesium molybdate occurs as belonesite, MgMoO4.

Magnesium phosphate occurs as bobierrite, Mg3(PO4)2.8H2O, in wagnerite, Mg3(PO4)2.MgF2, in struvite, (NH4)MgPO4.6H2O, and in luneburgite, Mg3(PO4)2.B2O3.8H2O.

Among the arsenates are - hoernesite, Mg3(AsO4)2.8H2O, cabrerite, (Ni,Mg)3(AsO4)2.8H2O, adelite, Ca(MgOH)AsO4, and tilasite, Ca(MgF)AsO4.

The following silicates have been identified in meteorites - enstatite and clinoenstatite, MgSiO3, diopside, MgCa(SiO3)2, hedenbergite, (Mg,Fe)Ca(SiO3)2, forsterite, Mg2SiO4, chrysolite, (Mg,Fe)SiO4, and some augites. Magnesium also occurs as silicate in talc or steatite, H2Mg3(SiO3)4, meerschaum, H2Mg2(SiO3)3, olivine, (Mg,Fe)2SiO4, and serpentine, Mg3Si2O7.2H2O.

Phlogopite or magnesia mica is K2O.2H2O.6MgO.Al2O3.6SiO2, and asbestos, which is very important industrially, is CaMg3(SiO3)4.

Geikielite is MgTiO3, and among the borates are - pinnoite, MgO.B2O3.3H2O, boracite, 2Mg3B8O15.MgCl2, and kaliborite, KMg2B11O19.9H2O.

Magnesium occurs also in spinel, MgO.Al2O3, hydrotalcite, Mg3Al(OH)6.3H2O, and kornerupine, Mg(AlO)2SiO4.

History of Magnesium

In 1695 Nehemiah Grew, a London physician, published an account of a medicinal salt obtained from the well-known mineral spring at Epsom. "Epsom salts" soon became famous, and are still used in medicine. George and Francis Moult established a factory in 1700 to obtain the salt from a spring at Shooter's Hill, near London. It was soon afterwards discovered by Friedrich Hoffmann in Seidlitz mineral water, and crystallised by Hoy from the mother-liquors of sea-water. The history of magnesium thus began with its sulphate, MgSO4.7H2O.

"Magnesia alba" was discovered, and its medicinal value observed, early in the eighteenth century. Since pyrolusite was then called magnesia nigra, the new substance was apparently named to contrast with it. Valentini in 1707, and Slevogt in 1709, prepared it from saltpetre mother-liquors. Partly because these preparations contained calcium carbonate, magnesia and lime were constantly confused till Black, in 1755, clearly distinguished them. He showed that magnesia alba was a compound of " fixed air " with a peculiar earth, which had a soluble sulphate. When Davy, in 1808, showed that magnesia was the oxide of a metal, he named the metal magnium. Finally, the name magnesium was adopted for the metal in magnesia, and manganese for the metal in pyrolusite. The latter had been known both as magnesium and manganesium.

"Magnesia" is derived from "magnesian stone," an alchemistic designation of the loadstone, and a stone shining like silver, which may have been talc. A confusion of pyrolusite with the loadstone may have led to the terms magnesia alba and magnesia nigra.

The metal was first prepared in mass by Bussy in 1829. He decomposed magnesium chloride with potassium; electrolytic methods are now used in industry.

Neighbours



Chemical Elements

3Li
6.9
Lithium
4Be
9.0
Beryllium
5B
10.8
Boron
11Na
23.0
Sodium
12Mg
24.3
Magnesium
13Al
27.0
Aluminium
19K
39.1
Potassium
20Ca
40.1
Calcium
21Sc
45.0
Scandium

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