Atomos: the Greek word for atom, meaning indivisible, is the ultimate component of matter according to the ideas developed by Leucippus and his disciple Democritus more than two thousand years ago. They suggested that all visible bodies are made of these unbreakable particles, and that the empty space between them is void. This early atomic theory is also called atomism, or atomic philosophy of nature.
Empedocles, living in the same period, affirmed that water, fire, air and earth constituted the four essential elements of which all matter was made. This is known as the four-element theory.
Aristotle adopted this proposition and it remained widely accepted until the eighteenth century. The atomic theory, although less acknowledged, was nevertheless preserved through the works of Epicurus and Lucretius.
Much of the civilizations developments (and their wars) are determined by the elements they know and the physical and chemical properties they master: mankind has risen from the iron and bronze ages, to the nuclear age, from the not so negligible potential lethal effect of the stone throw, to the massive destruction caused by the atomic bomb: the science of every epoch is paradoxically dedicated not only to the advancement of humanity, but to the slay of human beings as well.
Ten elements were known to the ancient world: carbon, sulfur, iron, copper, silver, tin, antimony, gold, mercury, and lead. Zinc ore was known, but the metal was not isolated until the 13th century in India.en elements were known to the ancient world: carbon, sulfur, iron, copper, silver, tin, antimony, gold, mercury, and lead.
Antimony compounds were used by the egyptians about 3000 BC, but the metal was not isolated until the 16th century in Europe.
In over 2000 years only three new elements were added to the yet unimaginable periodic table: arsenic, bismuth, and phosphorus.
In 1661 Robert Boyle wrote The Sceptical Chemist criticising the four-element theory and proposing for the first time the concept of an “element” as a substance that could not be split into any simpler substance.
In his book Elementary Treatise on Chemistry (1789) Antoine Lavoisier dealt more profoundly with the definition of a chemical element, and drew a table of simple substances. Some authors regard this table as the forerunner of the periodic table.
In 1808 John Dalton published the book New System of Chemical Philosophy, in which he established the modern atomic theory, based on the ideas of the ancient atomic philosophy of nature, but strongly supported with experimental data.
William Prout published a theory in 1816 (Prout’s hypothesis) affirming that all atoms, and hence all substances, are made of hydrogen. His idea was proven erroneous years later.
The first half of the 19th century was an age of splendour for chemistry: Dalton, Berthollet, Berzelius, Gay-Lussac, Avogadro, Dumas, Proust and many others advanced the scientific knowledge through experimental and theoretical innovations, including the discovery of twenty five new chemical elements.
In 1829 Johann Wolfgang Döbereiner published an article describing the triads: a relationship between certain elements in which some properties of the middle element are the mean of those of the other two. J. W. van Spronsen traces Döbereiner’s discovery back to 1817.
Leopold Gmelin also worked extensively on the triads in the following years. Several other scientists examined the numerical relationships between the elements during the 1850’s, among them Pettenkofer, Dumas, Kremers and Gladstone.
In 1862 Alexandre Emile Béguyer de Chancourtois, a French geologist constructed a three-dimensional representation of a periodic table: the “telluric screw”.
John Alexander Reina Newlands published an article in 1864 about what he called “the law of octaves”. Newlands observed an analogy between the periodicity of musical octaves and that of the chemical properties (a symphony of matter?).
In 1869 the Russian chemist Dimitri Ivanovich Mendeleev presented an article to the Russian Chemical Society comprehensively describing the arrangement of the elements according to a periodic system. The article was published in the Journal of the Russian Chemical Society in the same year.
The German physicist Julius Lothar Meyer accomplished a similar system in 1868, but it was published later than Mendeleev’s. A controversy has existed over who must be credited with the discovery of the periodic law. It is attributed by most authors to Mendeleev, since he defined the periodic law on a very detailed fashion, predicted new elements and drew many types of tables.
Although not agreed by all authors, it is believed that Mendeleev conceived his idea of the periodic table during a dream.
Between 1913 and 1914 Henry Moseley developed a method to exactly determine the number of unit charges (atomic number) on the nucleus. This number is equivalent to the quantity of electrons surrounding the nucleus. Since then the atomic number has been used, instead of the atomic weight, as the fundamental ordering principle for the periodic table.
More chemical elements were discovered throughout the years after Mendeleev, and by the early 1930’s the periodic table included the elements up to the atomic number 92 (uranium), with a few exceptions, namely 43 (technetium), 61 (promethium), 85 (astatine), and 87 (francium).
Elements 93 (neptunium) and 94 (plutonium) were artificially produced in 1940.
A series of papers published by Glenn T. Seaborg and others in Scientific American described the making of the synthetic elements, so named because they are produced by man using modern alchemy: nuclear transmutation.
In 1945 Seaborg arranged the heaviest elements (including elements 89 to 96) in a new series, which he named the “actinides”.
Elements 107 to 111 were made between 1981 and 1994 by a team of physicists led by Peter Armbruster, Sigurd Hofmann, and Gottfried Munzenberg at Gesellschaft für Schwerionenforschung (GSI, or the Institute for Heavy-Ion Research) in Darmstadt, Germany.
In 2005 a Joint Working Party of the International Union of Pure and Applied Chemistry (IUPAC), and the International Union of Pure and Applied Physics (IUPAP), confirmed the discovery of element with atomic number 112, made by the GSI team in Darmstadt, Germany. The name copernicium was approved for this element, with symbol Cn.
Elements 114 and 116
In 2012 a Joint Working Party of the International Union of Pure and Applied Chemistry (IUPAC), and the International Union of Pure and Applied Physics (IUPAP), confirmed the discovery of the elements with atomic numbers number 114 and 116. They adopted the names proposed by the discoveres, as follows: flerovium with the symbol Fl for the element with Z = 114, and livermorium with symbol Lv for the element with Z = 116.
Elements 113, 115, 117, and 118
In 1999 a group of scientists at the Lawrence Berkeley National Laboratory in California announced the discovery of elements 116 and 118. But their claim soon had to be retracted since the results could not be replicated by other laboratories.