Atomic structure, moles and periodicityThe periodic table is a guide or map to access specific information on different elements, such as: atomic mass, isotopic richness, spins nuclear, the electronic configuration and the position of the elements belong to which group and which period in the table. Over the past decades, many scientists have contributed to the improvement of the periodic table, but few have made the greatest influence and contribution to the periodic table, such as: Johann Dobereiner, John Newlands, Dmitri Mendeleev and Henry Mosley. Law of TriadsThe development of the periodic table begins with the German chemist Johann Dobreeiner. He collected similar elements. Its triads were groups of three similar elements for example: Calcium, Strontium and Barium in a single group. He noticed that the relative atomic mass of the middle element is the average of the other two elements. For example, the atomic mass of strontium is 88, so if you add the atomic mass of calcium which is 40 and that of barium which is 137 and divided by 2, you get 88, which is exactly the same atomic mass strontium. The law of octaves began with the English chemist John Newlands. classify the 60 known elements in order of increasing atomic mass. He noticed that after the space of eight elements, similar physical and chemical properties reappeared and each element was similar to the element eight placed further away. A problem with his table, he put Iron in the same group as Oxygen and Sulfur which are two non-metals. Then the Russian scientist, Dimitri Mendeleev continues in the path of John Newlans. He did the same thing as Newlands and he arranged the elements in order of increasing atomic mass, but he did a few extra things that made his table more successful and produced a much better table... middle of paper. ... ..o.uk/schools/gcsebitize/science/edexcel/patterns/periodictablerev5.shtml. Last accessed December 13, 2009. (2009). Periodic table. Available: http://www.chemicool.com/. Last accessed December 13, 2009. Dr. Edwin Thall. (-). Development of the periodic table. Available: http://mooni.fccj.org/~ethall/period/period.htm. Last accessed December 13, 2009-. (-). History of the periodic table. Available: http://en.wikipedia.org/wiki/History_of_the_periodic_table. Last accessed December 12, 2009.-. (-). History of the periodic table. Available: http://www.rsc.org/education/teachers/learnnet/periodictable/. Last accessed December 13, 2009. Ann and Patrik Fullick (1994). Chemistry. London: Heinemann Educational. -.Catrin Brown and Mick Ford (2008). Standard level chemistry. London: British Library Cataloging Data. –Word count: 1,145Works Citedwww.bbc.co.uk