atomic theory
Democritus was a Greek philosopher (born at Abdera in Thrace ca. 460 BC - died ca 370 BC). Democritus was a student of Leucippus and both believed that all matter is made up of tiny, indestructible bits which he called atoma or "indivisible units", from which we get the English word atom.
Atomic theory―Democritus is well known for his atomic theory. Democritus said that:
Everything is made of tiny bits he called atoma (indivisible units).These atoma are indestructible. Different shapes of atoma give them different properties. He guessed that things that tasted sweet were made of round atoma, while things that tasted bitter were made of sharp atoma. Changes we see are caused by the movement of the very tiny atoma. Democritus had no hard evidence. He came to these ideas simply by thinking about them. However, his ideas turned out to be somewhat close to what was discovered over 2000 years after his death.
http://simple.wikipedia.org/wiki/Democritus
In chemistry and physics an atomic theory explains what the basic structure of matter is like. It says that all of matter is made up of tiny parts called atoms, and attempts to explain what atoms are like. Atomic theory has changed over time, but one of the earliest known atomic theories was explained by the Greek philosopher Democritus. A lot of the ideas in the modern theory came from John Dalton, a British chemist and physicist.
The theory applies to solids, liquids and gases, but it does not apply to plasmas or neutron stars, where temperature and density stop atoms from forming.
Democritus atomic theory―During the cosmological era, the Ancient Greek philosophers were endeavoring to find an explication about the inception(beginning) of the Universe, and probing(investigate) for the main element. Some of them adverted(ref.attention) to it was water, some others the air, and others fire, as the element they mentally conceived(think) it was the main one.
Successively, in the atomicist era, inaugurated by Democritus (460 - 370 b.C.) in the 4th century B.C.. He proposed that when dividing matter many times, it should reach a point when the particle could not be divided anymore, but that should preserve the original properties of the matter. He named that particle the atom, that emanates(come) from Greek word ἄτομον, meaning without division. He proposed that atoms were eternal, immutable(unchangeable) and indestructible. Between an atom and another, there was just the nothing. He concluded that the properties of matter that are perceivable to us could be explicated by the properties and the conduct of the atoms, that can not be distinguished directly.
Democritus was right about the composition of the matter. In fact, elements like oxygen(O), nitrogen(N), carbon(C), and hydrogen(H) were composed of atoms of just one type, these being the fundamental basis to life and the explication to the constitution of the Universe. By example, the Universe contains in its composition a mass of 99% of hydrogen and helium (He); the Earths crust has a mass of 74,3% of oxygen and silicon (Si); the atmosphere, a 99% by mass of nitrogen and oxygen; the human body, 93% by mass of carbon and oxygen; and sea water, 55% chlorine(Cl) and 30,6% sodium (Na).
However, his theory was not valued at the time, and the scientific investigation commenced(begin,start) in late 19th century, remaining (until that moment) Aristotle's theory about the continuity of the matter, that meant it could subdivide infinitely in pieces every time more gradual, therefore, to know the composition of the matter is a theme that was suspended for a long time.
