Chemistry Reference
In-Depth Information
properties, such as
. The beginnings of gravimetric analysis in
the late eighteenth century required an additional shared property. The weight of a
whole was a sum of the weights of the parts. So, the possibility of determining
'
shape
and
bulk
'
'
'
'
atomic weight
'
became thinkable. As this principle was refined by the distinction
between
the two main mereological principles retained their
dominance. The properties of a whole were some function of the properties of the
parts, and the products of analysis of such wholes were constituents of the original
wholes. The reasoning from experimental results to atomic weights and the use of
the results of Aston
'
s mass spectrograph to identity elements depended on these
basic mereological rules, as did many other chemical methods and theories.
1
'
weight
'
and
'
mass
'
8.2 The Mereological Core of Chemical Thinking
Thinking in terms of wholes and their parts draws attention to several distinctions of
importance in chemistry.
(a)
Kinds of wholes:
Structural wholes consist of a collection of stable elementary
parts held together by at least some invariant relations, e.g. molecules, organic
and inorganic; dissipative wholes consist of bounded and stable array of
processes the material of which flows into and out of the system, e.g. flames,
smelting hearths (Earley
2005
).
(b)
Kinds of constituents
: those which retain their identity when detached from the
whole of which they are parts, e.g. molecules, atoms (ions), some organic
radicals; those the identity criteria of which change when detached from the
wholes in which they were parts, e.g.
In addition to the part/whole thinking that is the basis of the atomic theory in
chemistry there is also the way mass concepts, such as
and so on are
managed. Mass terms refer to extended substances which can be split into parts
which share those properties of the wholes from which they come that identified
them as substances. A gold ring is as much gold as the ingot from which it came.
A version of the basic mereology is involved in this domain too. To lay out the
principles of the mereology of mass substances Needham (
2005
) uses a distributive
condition that requires that each part of a mass substance is an instance of that
mass substance, and a cumulative condition, that the fusion of instances of a mass
substance is an instance of that mass substance.
These
'
water
'
,
'
gold
'
are similar to those of the corpuscularian mereology except
that the size, shape and mass of the
conditions
'
'
of mass substances are created by the
choice of the means by which parts are produced. The identity conditions for parts
and wholes of mass substances are contingent on choice of
parts
'
'
bucket
.
'
'
1
I will take the expression
atom-core
from Joseph Earley
s writings to cover free ions as well as
'
'
'
atoms in situ in stable molecular structures.
