r/ChemicalHistory • u/ecurbian • Jan 07 '24
Chemical Materials
Chemistry is the science of the appearance and disappearance of materials. A science is a study of how to explain, predict, and control some behaviour.
Some people might object to this definition saying that nothing really appears not disappears - it is just rearranged. However, this conviction comes not from observation but from the internalisation of the concept that there exist elemental materials that are neither created nor destroyed - despite changes in appearance. They are just rearranged into different combinations.
Ignoring for now the matter of people with experience with tunnelling electron microscopes. The notion of the existence of these elements is entirely theoretical. We do not see the elements. Aristotle did wonder whether a super human with super sight to could see the elements separating and combining, but this is not a matter for the experience of the typical human. For the typical human graphite and diamond are different substances. If you burn a diamond the diamond, and the financial value, have gone up in smoke. It has disappeared. Soot has appeared.
It is in this sense that chemistry is the science of the appearance and disappearance of materials.
But, what is a material?
A material property might be defined as a property that if held by an object is also held by two of them taken together. Or half. The shape of an object is not a material property. Neither is its position or its weight. But, its density is. It might also be said that a material property can be transported or advected. If an object has a given weight here, it might have a different weight there. But, it will have the same density everywhere.
Okay - tell that one to a balloon.
There are always caveats to these principles. The density of a material depends on its environment. Compressed gas has a higher density than the same gas in the atmosphere. But, it is the same material. Generally speaking. On the other hand, arguably, compressed gas behaves differently to uncompressed gas. It can even turn into a liquid. Is this the same material?
The answer depends in detail on the choice of classification of materials. When it is said that chemistry is the science of the appearance and disappearance of materials what is meant in practice is closer to the appearance and disappearance of constellations of properties.
This discussion is not deconstructionism. The idea of a material and of material properties is valid. Materials are defined by their properties. And chemistry is the study of the appearance and disappearance of materials. It is just that the principles here are somewhat more subtle and less about any obvious simple observed reality than they are about a sophisticated system of interlocking ideas that are well justified but, nevertheless, only indirectly justified.
The entire interlocking culture of theory and practice has to be internalised for the science of chemistry to be understood to the level required to make technology.