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Equivalence, Chemical
equivalence, two facts must be remembered. First, these num-bers are determined experimentally, hence are subject to error, both of observation and theory, and secondly, it is frequently multiples of these numbers that represent equivalence. Thus the amount of silver which is equivalent in a reaction to 65 of zinc is not 108, but twice 108 or 216. Except in the case of chlorine, a whole number is given as the atomic weight, although in some instances a fractional number might perhaps carry with it a somewhat greater probability of approximation to the actual truth. Take silver for instance; io7:66 may perhaps be a little nearer the actual truth than 108, but as many careful determina-tions have been made, and have given numbers between these limits, one has to choose somewhere, and for all ordinary calculations the whole numbers are usually taken, except in the case of chlorine.
Table of the more Important Elements and their Atomic Weights.
Name.
Symbol.
Atomic weight.
Aluminium
... Al
..... 27
Antimony
.. Sb (Stibium).
... 120
Argon
.. Ar
• .- 39(?)
Arsenic ...
.. As ...
..... 75
Barium
.. Ba ...
..... 137
Beryllium...
... Be ... .
9
Bismuth ...
... Bi
... 208
Boron
... B
11
Bromine ...
.. Br
... 80
Cadmium
... Cd .....
... 112
Caesium ...
.. Cs
... 132
Calcium ...
.. Ca ...
... 40
Carbon ...
.. C
12
Cerium
.. Ce ...
... 140
Chlorine ...
.. CI
- 355
Chromium
.. Cr
... 52
Cobalt
.. Co ...
- 59
Copper
.. Cu (Cuprum)
... 63
Erbium ...
.. Er .....
... 166
Fluorine ...
.. F .....
... 19
Gadolinium
.. Gd .....
. ... 156
Gallium ...
.. Ga .....
279
... 70