Humans have always been very curios creatures. The have always wondered about what they are and why they are here. Our limited knowledge of the environment has always urged for new things to be discovered. The desire to understand the world better has made people search for rational answers, for principles and laws. For centuries people have tried to unlock the mysterious world that surrounds them.
Because myths did not explain things well enough the Greeks began to ask questions about the world around them. They did this so thoroughly and so brilliantly that the era between 600 and 400 B.C. is called the golden age of philosophy. The Greek philosophy was an attempt to find the truth about unexplained phenomena, mostly by trying to think things through, not by running experiments in a laboratory. The philosophers wanted to discover the basic nature of things and some of them believed that they could find one thing that everything else was made of. A philosopher named Thales said that this substance was water, but another named Anaximenes thought it was air. A third called Empedocles said that the world was composed of four elements: earth, air fire and water.
Aristotle became the most influential of the Greek philosophers, and his ideas dominated science for nearly two millennia after his death in 323 BC. He believed that four qualities were found in nature: heat, cold, moisture, and dryness. The four elements were each composed of pairs of these qualities; for example, fire was hot and dry, water was cold and moist, air was hot and moist, and earth was cold and dry. These elements with their qualities combined in various proportions to form the components of the earthly planet. Because it was possible for the amounts of each quality in an element to be changed, the elements could be changed into one another; thus, it was thought possible also to change the material substances that were built up from the elements-lead into gold, for example.
During this period the Greeks had laid the basic foundation for one of our main ideas about the universe. Leucippus and Democritus established the idea of the atom in an effort to figure out the ultimate composition of things. At that time there was no way to test whether atoms really existed, and more than 2000 years passed before scientists proved the theory.
Meanwhile, the Egyptians were already practicing the art of chemistry. They were mining and purifying the metals gold, silver and copper. They were making embalming fluids and dyes. They called this art khemia, and it flourished until the seventh century A.D., when it was taken over by the Arabs. The Arabs changed the word khemia to alkhemia. Today our version of the word, alchemy is used to describe everything that happened in chemistry between A.D. 300 and A.D. 1600.
The main goal of the alchemists was the conversion of base metals into gold. They wanted to turn one element into another. The ancient Arabic emperors employed many alchemists to try and change mercury, copper and other less worthy metals into gold.
At almost the same time, and probably independently, a similar alchemy arose in China. Here, also, the aim was to make gold, although not because of the monetary value of the metal. The Chinese believed that gold was a medicine that could grant long life or even immortality on anyone who consumed it. As did the Egyptians, the Chinese gained practical chemical knowledge from incorrect theories.
Alchemists also tried to find the philosophers stone and the elixir of life. They wanted, in other words, to discover a cure for all diseases, and a method of indefinitely prolonging life. In the early 13th century alchemists like Roger Bacon, Albertus Magnus and Raymond Lully began to realize that the search for a philosopher’s stone was useless. They believed that alchemists would better serve the world by discovering new products and new methods to improve everyday life. This started a trend in which alchemists gave up on finding the philosophers stone. An important leader in this movement was a Swiss by the name of Theophrastus Bombastus.
Bombastus felt that the object of alchemy should be the cure of the sick. He believed that salt, sulphur and mercury would give health if they were present in the body in proper proportions. This was the first period of iatrochemistry. The last influential chemist in this era was Robert Boyle. In his book, The Sceptical Chymist Boyle rejected the leading scientific theories of his day and started the list of elements, which are still recognized today. He also formulated a law relating to the volume and pressure of gasses. In 1661 he founded a scientific society, which later became known as the Royal Society of England.
In the course of their work, the early alchemists discovered acetic acid, nitric acid and ethyl alcohol, as well as many other substances used by chemists today. Their discoveries led the way to modern chemistry. By the mid 17th to 19th centuries scientists were using the modern method of discovery by testing theories with experiments. One of the great controversies during this period was the mystery of combustion. Two chemists, Johann Joachim Becher and Georg Ernst Stahl proposed the theory of phlogiston. This theory said that an essence (like hardness or yellowness) was supposed to escape during the process of combustion. No one could prove the theory of phlogiston.
The first chemist proved that oxygen was essential to combustion was done by Joseph Priestly. Oxygen and Hydrogen were both discovered during this period. The French chemist, Antoine Laurent Lavoisier formulated the present accepted theory of combustion. This era marked the first time in which scientists used the modern method of testing theories with experiments. This led to a new era known as Modern Chemistry, which many also refer to as Atomic Chemistry.
Chemistry in todays world:
Chemistry has had an enormous influence on human life. In earlier periods chemical techniques were used to separate useful natural products and to find new ways to use them. In the 19th century techniques were developed for synthesizing completely new substances that were either better than the natural ones or could completely replace them more cheaply. As the complexity of synthesized compounds increased, wholly new materials with new uses began to appear. Plastics and new textiles were developed, and new drugs conquered whole classes of disease. Physicists, biologists, and geologists had developed their own techniques and ways of looking at the world, but now it became evident that each science, in its own way, was the study of matter and its changes. Chemistry lay at the base of each of them. The resulting formation of such interscientific disciplines as geochemistry or biochemistry has stimulated all of the parent sciences.
The progress of science in recent years has been spectacular, although the benefits of this progress have had some corresponding liabilities. The most obvious dangers come from radioactive materials, with their potential for producing cancers in exposed individuals and mutations in their children. It has also become apparent that the accumulation in plant and animal cells of pesticides once thought harmless or of by-products from manufacturing processes often have damaging effects. These dangerous materials have been manufactured in enormous amounts and dispersed widely, and it has become the task of chemistry to discover the means by which these substances can be rendered harmless. This is one of the greatest challenges science will have to meet.
Today, no part of our lives is untouched by the science of chemistry. Many good and bad applications of modern chemistry are around us everywhere. Our clothes, furniture, food and drugs that heal our illnesses are all products of applied chemistry. Fuels, explosives and building materials are all made possible by synthetic chemistry.
Chemistry is truly a powerful tool. It can create a better future for us, or if misdirected, can lead to our doom. Its essential that we study chemistry and understand its principles. It will help us understand ourselves and the world we live in. Because todays world is more than ever based on the science of chemistry.
Time Line of Chemistry:
600 B.C. Thales Water is the main form of matter
546 B.C. Anaximenes Air is the main form of matter
450 B.C. Empedocles Idea of the four elements
420 B.C. Democritus Idea of the atom
400 A.D. Ko Hung Attempts to find the elixir of life
1000 Avicenna Book of the Remedy
1330 Bonus Introduction to the Arts of Alchemy
1500 Little Book of Distillation
1620 Van Helmont Foundations of chemical physiology
1625 Glauber Contributions to practical chemistry
1661 Boyle The Sceptical Chymist
1766 Cavendish Discovery of hydrogen
1775 Lavoisier Discovery of the composition of air
1787 Lavoisier & Berthollet A system of naming chemicals
1800 Proust Law of Definite Composition
1800 Dalton Proposes an atomic theory
1820 Berzelius Modern symbols for elements
1829 Dbereiner Law of Triads
1860 Bunsen & Kirchhoff Spectroscopic analysis
1869 Mendeleev Periodic Law
1874 Zeidler Discovery of DDT
1874 Vant Hoff & Le Bel Foundations of stereochemistry
1886 Goldstein Naming of cathode rays
1897 Thomson Proposes a structure of the atom
1905 Einstein E=mc2
1908 Gelmo Discovers sulfanilamide
1911 Rutherford Proposes the nuclear atom
1913 Bohr Proposes energy levels in atoms
1922 Banting, Best & Macleod Discover insulin
1928 Fleming Discovers penicillin
1932 Urey Discovers deuterium
1942 Fermi First atomic pile
1945 First atomic bomb; nuclear fission
1950 Pauling Helical shape of polypeptides
1952 First hydrogen bomb; nuclear fusion
1953 Watson & Crick Structure of DNA
1958 Townes & Scawlow Develop laser beam
1969 Discovery of first complex organic interstellar molecule- formaldehyde
1970 Ghiorso Discovers element number 105
1973 Cohen, Chang, Boyer and Helling Initiation of recombinant DNA studies
1974 Seaborg & Ghiorso Discovery of element 106
1979 A. Crewe First color motion pictures of individual atoms