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What is hydrogen?
Why is hydrogen?
In History
In Chemistry
The Atom
Atomic weight
Isolution
Uses
Uses in IC Engines
Fuel cells
The Perodic
Table Of The Elememts |
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What is hydrogen?
Why is hydrogen?
In History
In Chemistry
The Atom
Atomic weight
Isolution
Uses
Uses in IC Engines
Fuel cells
The Perodic
Table Of The Elememts |
Notes about
atomic weights
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Some values of atomic weights are labelled with one or more of the letters
g, m, and r. The meaning of these is as follows (but follow the atomic
weight hyperlink above for further information):
g: geological specimens are known in which the element has an isotopic composition outside the limits for normal material. The difference between the atomic weight of the element in such specimens and that given in the table may exceed the stated uncertainty. m: modified isotopic compositions may be found in commercially available material because it has been subjected to an undisclosed or inadvertent isotopic fractionation. Substantial deviations in atomic weight of the element from that given the table can occur.
r :range in isotopic composition of normal terrestrial material prevents
a more precise atomic weight being given; the tabulated atomic weight value
should be applicable to any normal material.
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