Chemistry Reference
In-Depth Information
scales which have been completely unreachable until now. Chemists have gained
an enlarged capacity to synthesize, scrutinize, and modify particle size and distri-
bution, agglomeration state, shape, crystal structure, chemical composition, surface
area, surface chemistry, surface charge, porosity, and interfaces.
A “science of individuals or particulars” arises and chemists are now able to
generate and study multifarious details at the individual level (Llored
2013
).
Non-stoichiometric compounds are now legion. Chemists even contrive to combine
organic and inorganic ingredients into the same hybrid body; thus, holding together
types of chemistry which have always been incompatible hitherto. This example
strengthens the above mentioned ideas of the
indeterminacy
and
open
-
endedness
of
what is operationally defined. Fran¸ois Dagognet states:
We must accept the
continuous renewed and inexhaustible richness of what is extended
'
(Dagognet
1989
, p. 166). This diversity is not solely a question of ingredients, quantities, and
structure. It also depends on the devices and the instruments involved. As a
consequence, it is a question of
contextuality
too. Let us take the example of the
synthesis of a solid sample of CaCO
3
in order to highlight the role played by the
context both in the synthesis and the definition of a chemical body.
Starting from different ingredients, particles will grow to attain different final
sizes and morphologies (Aimable et al.
2013
). Thus, the end product may appear
completely different, depending on whether a reactive material is added all at
once or gradually. By adding a small amount of fine material to be precipitated
(i.e., seeds), one can better control the apparently chaotic nucleation step. For
example, adding calcite seeds allows for the precipitation of pure calcite. On the
other hand, without seeds, one obtains a mixture of calcite and vaterite with a larger
particle size distribution and various morphologies. The body CaCO
3
depends on
the process used and on the time employed. This body is furthermore distributed or
size-dispersed in the sense that the sample does not contain a single body CaCO
3
but, on the contrary, encompasses many similar bodies CaCO
3
which differ in
size.
Neither the device nor the history of the chemical reaction can be eliminated
from the final result. Operations are thus part of the definition of the
“
nanobody
”
under study
.
The mode of access cannot be eliminated from the final product insofar as it
contributes to the determination of the whole body and its correlative parts and
structure. The structure of the crystals may also differ if the chemical device
changes. It can even differ within the same particular chemical device, depending
on the size of the crystals, which itself depends on the environment.
In a nutshell
,
the internal arrangement can be grain
-
size sensitive
:
The concept of structure thus
sometimes becomes
,
at least partly
,
extrinsic
!
Accordingly, chemists have to hold the composition, the global and internal
structures, the parts of the body, the whole body itself, the environment, and the
device together within the same coherent explanation. If a chemical body is thus
tied to
praxis
, it is not a definite something or mere substrate that endures
through time. Instead, it is at all times fully realized as just what it appears to be,
and at the same time it never stays the same as it becomes transformed in processes
of making, remaking, and learning to make. As an indefinite “something out there”
'
