Chemical elements
    Physical Properties
      Atomic Weight, History
    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
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    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
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    PDB 1uik-1vc9
    PDB 1vcl-1vsd
    PDB 1vst-1wax
    PDB 1wb1-1wzn
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    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
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    PDB 2d1k-2dw6
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    PDB 2eh3-2f6t
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    PDB 2gl6-2h7v
    PDB 2h7x-2hne
    PDB 2hny-2i34
    PDB 2i3d-2io7
    PDB 2io8-2j3e
    PDB 2j3q-2jg1
    PDB 2jg2-2nvu
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    PDB 2ofw-2our
    PDB 2ous-2pcl
    PDB 2pda-2px3
    PDB 2pxi-2q5z
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    PDB 2qm1-2qwy
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    PDB 2w83-2wi3
    PDB 2wia-2wzd
    PDB 2wzg-2xcp
    PDB 2xdg-2y0s
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    PDB 2zkj-301d
    PDB 302d-3a5k
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    PDB 3ak9-3bb3
    PDB 3bb4-3bsu
    PDB 3btx-3c95
    PDB 3c9h-3ckg
    PDB 3clc-3cxc
    PDB 3cxo-3der
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    PDB 3du7-3e84
    PDB 3e8m-3eni
    PDB 3eno-3ezw
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    PDB 3g45-3gj3
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    PDB 3hs0-3hzt
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    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

Atomic Weight of Magnesium, History

The atomic weight of magnesium, which has always been recognised as a divalent element, has been determined by the following methods: -

  1. The conversion of the oxide into the sulphate.
  2. The ignition of the sulphate to the oxide.
  3. The precipitation of magnesium sulphate with barium chloride.
  4. The precipitation of magnesium chloride with silver nitrate.
  5. The ignition of the oxalate into the oxide.
  6. The ignition of the carbonate into the oxide.
  7. The conversion of the metal into the oxide.

In 1884 Marignac critically reviewed the determinations of the atomic weight of magnesium, and obtained the ratio

MgO:MgSO4 = 100:298.27

as the mean of ten conversions of the pure oxide into the sulphate, and the ratio

MgO:MgSO4 = 100:298.31

as the mean of twelve ignitions of the sulphate into the oxide.

Using the atomic weights O = 16 and S = 32.065, these results calculate to atomic weights for magnesium of 24.38 and 24.37 respectively. Burton and Vorce, in 1890, obtained the ratio

Mg:MgO = 100:165.877

by converting the carefully purified metal into the nitrate and igniting to the oxide. This result, which is the mean of ten determinations, gives an atomic weight of 24.287 for magnesium, if O = 16.

Dumas, in 1859, as the mean of eleven determinations, obtained the ratio

MgCl2:2Ag = 100:225.91

by estimating the silver after precipitating magnesium chloride with silver nitrate. Using atomic weights Cl = 35.457 and Ag = 107.880, this result gives 24.59 for the atomic weight of magnesium. Dumas was not very confident in his result, since he found it difficult to ensure the purity of his magnesium chloride, but he decided that it was probably better to retain 12 as the equivalent of magnesium instead of the 12.5 of Berzelius, pending further investigation.

Richards and Parker, in 1897, obtained the following results. Both their atomic weights for magnesium, calculated by using O = 16, Cl = 35.456, and Ag = 107.930, and atomic weights calculated from the fundamental data used in this series, namely, Ag = 107.880 and Cl = 35.457, are given.

In 1909 the International Commission on Atomic Weights altered the value from the 24.36 then in use to 24.32, and this value was retained in 1925.

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