12.7 What are "heavy" metals? (Chemistry)
Description
This article is from the Chemistry FAQ, by Bruce Hamilton B.Hamilton@irl.cri.nz with numerous contributions by others.
12.7 What are "heavy" metals? (Chemistry)
There appears to be no standard definition, however the general consensus
appears to be all metals with a density greater than 4 or 5 [8,9,10]. If
you also consider the conventional analytical chemistry definition of "heavy
metals" ( precipitation of sulfides from acidic solutions ), you obtain
quite a diverse mixture of possible candidates. Moving the density limit
from 4 to 5 really only just impacts on Ti, Y and Se. Some other texts use
more complex definitions that may also include accepted "light" metals with
densities less than 4, eg Hawley uses "A metal of atomic weight greater
than sodium (22.9) that forms soaps on reaction with fatty acids. e.g.,
aluminum, lead, cobalt". The term " heavy-element " is commonly used to
describe the transfermium elements, - elements with an atomic number
greater than 100.
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