History of the Atom

The illustration shows alchemists working in their labs trying to transmute lead into gold and seeking the ultimate goal of alchemy: the Philosopher’s Stone and the Elixir of Life. As alchemists try to understand the nature of matter, they also added significant contributions in the study of medicine.

             For centuries, humans have pondered the origin of his existence. Since time immemorial, we have asked ourselves the question “Where did we come from?” Scientists in the middle ages did several experiments to study the nature of matter but their ideas did not originate from themselves. Greek philosophers have asked the same question and arrived at several answers which we are about to discuss.

 EARLY IDEAS ABOUT THE ATOM

               The chemistry that we know today actually started from the minds of philosophers more than 2000 years ago. But before the conception of science, ancient civilizations never had the idea that they were already using the concepts of chemistry. People knew how to make perfumes, paints, armors made out of metal ores. They also know pottery, baking, and dye-making but they do not know the science behind all of those processes. This period of development of science is called as the period of Practical Arts (---- to 600 B.C.). These processes had no scientific basis and craftsmen only relied on their experiences in making their products.

                         Later on, people started asking questions about what was happening around them. Greeks, in particular, starting studying the philosophical or theoretical aspects of the processes that they were using. This period was called the period of Greek Theory (600 B.C. to 300 B.C.). Below are the list of some noted Greek philosophers and their ideas about the nature and origin of matter:

1.       Thales of Miletus

Thales of Miletus

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He said that matter came from water. He got this idea when he was surveying the banks of the Nile River. Every time it rains and the Nile Delta overflows, he sees different kinds of plants and animals coming out of the water. He also observed that the soil in the river banks becomes more fertile after the water had subsided. He, therefore, concluded that everything comes from water.

2.       Democritus

Democritus

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He believed that matter is made up of tiny indivisible particles he called atomos which literally means “uncut” or “indivisible”. He also believed that this atomos should be eternal because everything could be broken down into smaller pieces, then nature would dissolve like constantly diluted soup. Democritus actually got this idea from his teacher Leucippus, but what made his idea different was that he described atomos even further. He said that atomos contains “hooks” and “barbs” that enable them to interact with other particles to form new substances.

1.       Empedocles

Empedocles

è A philosopher from Sicily who believed that matter is composed of four elements, namely: earth, air, fire, and water. He also said that everything around us is made from the the combination of these elements in varying proportions. When you burn a piece of wood, you hear it crackle because of “water” evaporating, we see smoke because of “air”, the “fire” that we can see, and the ash that remains after burning as the “earth”. This idea of the composition of matter became very popular nowadays since a lot of movies make use of this idea as their main theme.

Aristotle

2.       Aristotle

è He believed that matter can be infinitely divided into smaller pieces. He also supported the idea of Empedocles about the four elements.

These philosophical and mystical ideas of the Greeks was combined with the practical arts of the Egyptians in Alexandria which gave birth to a new field of interest for many scientists, the period of Alchemy (300 B.C. to 1650 A.D.). The dominant idea for most alchemists was that base substances, like copper or lead, can be purified with fire and transmute it to form gold. Just like humans, when tested with trials become strong and perfect, matter can also be purified with fire and become the perfect metal during those times, gold. They also believed that if an alchemist was able to transmute a base metal into gold, he can also achieve a very powerful transmuting agent called the Philosopher’s Stone. When alchemy reached the Arabs, they called the Philosopher’s Stone as elixir, the substance that could cure all diseases at give man eternal life by preventing death.

In 1667, a scientist named Johann Joachim Becher postulated that a substance called phlogiston is released when a substance is burned. In 1703, Georg Ernst Stahl, a professor of medicine and chemistry in the University of Halle in Wittenberg, proposed the Phlogiston Theory. According to this theory, when a substance is burned, phlogiston is released into the air and a phlogiston-free ash is left:

Wood à ashes + phlogiston (released into the air)

In the same manner, when a metal is burned, it also releases phlogiston into the air, leaving a phlogiston-free substance called calx.

Metal à calx + phlogiston (released into the air)

One flaw that the Phlogiston Theory supporters was not able to resolve was that when a metal is burned, it should leave a phlogiston-free calx that should weigh less than the metal. But in reality, calx weighs more than the metal. Phlogiston Theory supporters were not able to explain why the calx, which was removed with phlogiston, is heavier than the metal. Nevertheless, this theory dominated most of the eighteenth century until Antoine Lavoisier revolutionized the experimentation process.

Antoine Lavoisier

Antoine-Laurent de Lavoisier, a French Nobleman, debunked the Phlogiston Theory and paved the way for the period of Modern Chemistry (1790 – present). He was able to explain why calx is heavier than its metal by using balances when conducting his experiments. He was also able to do this with the help of Joseph Priestley’s invention of the Oxygen gas. Lavoisier found out that a substance burns, not because phlogiston is released into the air, but because oxygen gas reacts with the substance. In the case of a burning metal, oxygen gas combines with the metal forming a metal oxide, which makes it heavier.

Metal + Oxygen Gas à metal oxide

He also noted that mass is neither created nor destroyed in an ordinary chemical reaction. Thus, the mass of the reactants should also be equal to the mass of the product. This idea is now called the Law of Conservation of Mass. Because of his contributions, he is now called the Father of Modern Chemistry. Sad to say, he was one of the tax collectors who were tried and guillotined during the Reign of Terror in France in 1794.