In philosophy for substance, from Latin substantia , traced from the greek ὐ ποκέιμηνον ( hypokeimenon ), literally translated as "what is below" means that which is hidden within the sensible thing as its ontological foundation. The substance is intended as indispensable, constitutive of everything that it stands out from what is accessory. [Quote ]. Surprisingly enough, yes, but True, it was the philosophy, the philosophy astratteggiante to insinuate a doubt in the "scientists" of the time, especially in Greece to seek to move their interest in what "was" the smallest part of what stood before him. Democritus, having wandered for years to "the whole earth" came to reflect on what exists and is tangible, the substance, and what does not exist, yet. Do not address only the substance, but Democritus had a brilliant intuition and curiosity, he thought the substance was in turn composed of sub-substances, and they in turn were made by sub-sub-substances, until you get to the heart of the substance, a sub-substance but it appears indivisible, a ἄ τομος "Atomos, the fact indivisible. Democritus arrival of a sensational discovery (certainly not based on observations or experiments, we have to wait for that Rutherford and Physics 900) the substance was organized into atoms, and these atoms were the real substance, understood as that which is "it" and that feature the "thing" that makes itself. From here, the concept of substance in chemistry, which is different on the basis of its atoms that compose it: if the atoms are the same (eg O 2, N 2 and diatomic molecules in general) refers to a simple substance, if not identical atoms (eg H 2 O, CH 3 COOH) refers to compound substances. Everything starts and then the substance, which is composed of atoms that "organize" and form a simple or a compound, derived from them all other kinds of "mixture" and "solution" consisting of various substances, which can mix or not, maintain their characteristics or not. Now that the "substance" of the speech were known to everyone in the scientific community there is the question was not indifferent to having to take measures on the substance of the measures that could describe it, of course, could be weighed, but only if there were large quantities of the same, imagine how it was possible to weigh "a few" atom with scales? ! Thankfully, Wilhelm Ostwald in 1896 introduced the concept of mole, the sense of "amount of substance that contains a number of atoms equal the number of atoms in 12g of C 12 definition which results in the definition" school "of "The mass in grams equal to the molecular weight. Since 1976, the Mole (mol) became part of the SI (prior to that date had and the grammoli grammolecole) since 2002 and is the only way to measure the amount of chemical in Italy and around the World.
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