We explain what a substance is in chemistry, what types exist and differences with compounds. Furthermore, the substance in philosophy.
What is a substance?
A substance is the most essential part of something, that is, matter in its most stable, specific and invariable state. It is not easy to define the substantial, and philosophy, on the one hand, and chemistry, on the other, are largely responsible for this: the first from a conceptual point of view, the second from the scientific point of view.
When referring to the substance of something, we are pointing to its essential, central, purest part: that which is not composed of other substances, but of itself and, therefore, also the most important, defining, nuclear part.
That's why, chemistry distinguishes between substances and compounds since by reacting two or more substances we can obtain a compound. However, depending on the nomenclature, it is also possible to speak of “simple substances” and “compound substances” in these cases.
Similarly, we use this term to refer to things that have value in themselves that is, they contribute something, they are dense. “An insubstantial comment,” for example, is a comment that has no substance and, therefore, has no value, it is empty.
In another sense, “a substantial dinner” is a nutritious, abundant meal, full of content and therefore good, desirable.
See also: Homogeneous mixture
Substance in chemistry
Chemistry defines substances as those homogeneous types of matter, endowed with a defined and fixed chemical composition. Substances are composed of molecules, and these in turn of atoms, that is, particles chemically linked together in a fixed and stable way.
Substances are different from mixtures, which are combinations, distinguishable or not, of two or more substances to form a single matter (called, depending on the case, solution, dissolution, alloy, etc.).
Something different happens when two substances react chemically, and combine through molecular bonds and changing their nature. Thus it gives rise to a compound (or compound chemical substance), that is, a new chemically stable substance.
Examples of chemical substances are:
- Simple (formed by the same type of element). Gold, oxygen, nitrogen, argon, iron, fullerene.
- Composite (made up of two or more types of elements). Water, glucose, carbon dioxide, ammonia.
The chemicals cannot be separated by any physical separation method (such as decantation, filtration or evaporation). Each substance has specific properties, such as melting point, boiling point and density. Each substance also exists in a certain state of aggregation (solid, liquid, gas, plasma).
Substance in philosophy
Philosophically speaking, the substance of things is their essence or their being understood as an intrinsic property of the thing, something that is “underneath” or that “underlies” the accidental qualities of matter. When changing a substance structurally, we are essentially changing one substance for another.
Since ancient times, attempts have been made to define what substance is. Aristotle (4th century BC) defined it as “that which is neither predicated of a subject nor present in a subject, for example, a man or an individual horse.” While René Descartes (1596-1650), one of the fathers of modern philosophy, defined it as “everything that does not need anything else to exist.”
Continue with: Pure substance
References
- “Chemical substance” in Wikipedia.
- “Substance (philosophy)” on Wikipedia.
- “Substance” in the Language Dictionary of the Royal Academy of the Spanish Language (RAE).
- “What is a Chemical Substance” (video) at The Audiopedia.
- “Substance (philosophy)” in The Encyclopaedia Britannica.
