The Periodic Table as we know it today came to fruition one February’s day in St. Petersburg in 1869. Mendeleev was in the process of writing a new textbook on inorganic chemistry for his students at the Unisversity of St. Petersburg when he decided to organize his material in terms of the families of the known elements which displayed similar properties. Over the years Mendeleev had obtained extensive amounts of data on the unknown elements such as their atomic weights, their roles in chemical reactions and their melting temperatures. (2.) Legend has it in the Chemistry world that the idea and form of the Periodic Table came to him a dream during his afternoon nap. This occurred after he had devoted himself to a complex card game that involved creating a card for each of the 63 known elements at that time. This idea came to him after he had noticed patterns in the properties and atomic weights of halogens, alkali metals and alkaline metals. In particular he observed similarities between theseries Cl-K-Ca , Br-/Rb-Sr and I-Cs-Ba. The card game served to extend this emerging pattern to other elements. With the elements symbol, atomic weight, and characteristic chemical and physical properties written on each card he arranged the cards on a table in order of ascending atomic weight grouping elements of similar properties together in a manner not unlike the card arrangement in his favorite solitare card game, patience, the periodic table was formed.(3.) Mendeleev was justifiably convinced that he had made a major scientific breakthrough and published his work ‘On the Relationship of the Properties of the Elements to their Atomic Weights’ in 1869.
Clearly Mendeleev was not the sole contributor to everything contained in the Periodic Table. He needed a thorough understanding of all the known elements that had been discovered up to the point of his creation. The history of elements can be traced back to the prominent Greeks at around 400B.C. The scholar Democritus was a pioneer in his way of thinking at this time. He thought that materials such as fire were made up of tiny invisible particles that could not be broken into smaller pieces. The word that he coined for these particles was the Greek for atoms, atomos . Atoms are of course, the particles which make up elements.
Philosopher Aristotle also helped further with the understanding of how elements behaved with his idea that the four ancients elements could be mixed into any kind of material. This prompted a century’s long interest in alchemy. (4.) Although alchemy came to be abused somewhat by conmen trying to make gold, there were many who worked like scientists . Their efforts paved the way for the first true chemists and the modern definition of an element.
Only after many centuries did scientists begin to doubt whether there were not more than 4 elements. In the late 17th and early 18th centuries, laboratories around Europe were discovering new elements such as Phosphorous. It was at this time that the idea of the atom was gaining more credibility through the works of Scottish alchemist Robert Boyle who argued that all matter must be made of atoms that come in differing shapes and sizes. In 1789 French chemist Antoine Laurent de Lavoisier offered the first modern definition of an atom; a chemical substance that could not be broken down into another substance. (5.) Englishman John Dalton then suggested that there were different kinds of atoms behind different elements and revolutionised a way to estimate the weight of an atom.
Mendeleev’s table was brilliant, a real discovery at the time. The science world was amazed by the new theory and a step forward in discovering the truth behind the building blocks of matter was made. However, the table was not complete, had some false points and work had to be done to develop it. Mendeleev’s table did explain the periodic nature of elements (that a relationship is to be found between elements) but it was modern scientists that had to discover why this was so and the laws that determine these relations. Of course, all modern discoveries were inspired by the new table Mendeleev created and did further develop his findings to extend our knowledge of the world.
In 1911 Ernest Rutherford studied the atom more closely and discovered the nuclear charge. This nuclear charge on a nucleolus was is relationship with the atomic weight of elements. Other scientists at the time felt that this relationship exists. It meant that the science world was working hard on the problems that arrived after Mendeleev’s table. The charge was named - atomic number and this new discovered property of elements gave scientists the tools to further organize the table of Mendeleev. Later on, Henry Moseley’s work on x-rays and wavelengths of elements showed that they were, as well, in relation with the atomic number. When the isotopes of elements were found it was realised that the periodic law followed rules and properties more complex that just the atomic weight of elements.
It was Niels Bohr who created a new and influential theory. He studied and discovered that electrons organize into shells – they occupy different energy levels. Another scientist, G.N. Lewis, further developed Bohr’s studies and found that electrons bond into pairs when occupying an energy level. Later, Glenn Seaborg worked to find the plutonium in 1940 and all the transuranic elements. He did make some important reorganization of elements order (related to his work) as well. All this work lead to the development of science and the latest scientific news report of a collider construction - a huge machine using magnetic fields to collide parts of atoms aiming at looking at what they are made of and finding the smallest possible particle.
It was Niels Bohr who created a new and influential theory. He studied and discovered that electrons organize into shells – they occupy different energy levels. Another scientist, G.N. Lewis, further developed Bohr’s studies and found that electrons bond into pairs when occupying an energy level. Later, Glenn Seaborg worked to find the plutonium in 1940 and all the transuranic elements. He did make some important reorganization of elements order (related to his work) as well. All this work lead to the development of science and the latest scientific news report of a collider construction - a huge machine using magnetic fields to collide parts of atoms aiming at looking at what they are made of and finding the smallest possible particle.
To conclude in 1869 Mendeleev introduced his famous periodic table. It was the work of a man passionate about science and the result of hard intellectual endeavours. The ancient Greeks began their search for truth and started asking about the building blocks of matter followed by the alchemic study and the atom weight discovery, done by John Dalton. It was Mendeleev that demonstrated the periodic relations between elements and it moved knowledge to a more scientific stage opening the door for other researchers to develop more precise models of the elements and chemistry.
(1.) http://www.wou.edu/las/physci/ch412/perhist.htm (accessed on 16/2/11)
(2.) http://books.google.co.uk/books?id=qemsEdmafYEC&pg=PA5&dq=periodic+table+history&hl=en&ei=TL1bTZz3BYqJhQe52vnJDQ&sa=X&oi=book_result&ct=result&resnum=3&ved=0CDgQ6AEwAg#v=onepage&q=periodic%20table%20history&f=false (accessed on 16/2/11)
(3.) http://www.wou.edu/las/physci/ch412/perhist.htm (accessed on 16/2/11)
(4.) http://books.google.co.uk/books?id=qemsEdmafYEC&pg=PA5&dq=periodic+table+history&hl=en&ei=TL1bTZz3BYqJhQe52vnJDQ&sa=X&oi=book_result&ct=result&resnum=3&ved=0CDgQ6AEwAg#v=onepage&q=periodic%20table%20history&f=false (accessed on 16/2/11)
(5.) http://books.google.co.uk/books?id=qemsEdmafYEC&pg=PA5&dq=periodic+table+history&hl=en&ei=TL1bTZz3BYqJhQe52vnJDQ&sa=X&oi=book_result&ct=result&resnum=3&ved=0CDgQ6AEwAg#v=onepage&q=periodic%20table%20history&f=false (accessed on 16/2/11)
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