Peridoic Table

Facts of the periodic table
While Dmitri Mendeleev is most often cited as the inventor of the modern periodic table, his table was just the first to gain scientific credibility, and not the first table that organized the elements according to periodic properties.
There are 90 elements on the periodic table that occur in nature. All of the other elements are strictly man-made.
Technetium was the first element to be made artificially.
The International Union of Pure Applied Chemistry, IUPAC, revises the periodic table as new data becomes available. At the time of this writing, the most recent version of the periodic table was approved 19 February 2010.
The rows of the periodic table are called periods. An element 's period number is the highest unexcited energy level for an electron of that element.
Columns of elements help to distinguish groups in the periodic table. Elements within a group share several common properties and often have the same outer electron arrangement.
Most of the elements on the periodic table are metals. The alkali metals, alkaline earths, basic metals, transition metals, lanthanides and actinides all are groups of metals.
The present periodic table has room for 118 elements. Elements aren 't discovered or created in order of atomic number. Scientists are working on creating and verifying element 120, which will change the appearance of the table.
Although you might expect atoms of an element to get larger as their atomic number increases, this does not always occur because the size of an atom is determined by the diameter of its electron shell. In fact, element atoms usually decrease in size as you move from left to right across a row or period.
The main difference between the modern periodic table and Mendeleev 's periodic table is that Mendeleev 's table arranged the elements in order of increasing atomic weight while the modern table orders the elements by increasing atomic number.

Times of the periodic table
440 BC Democritus and Leucippus propose the idea of the atom, an indivisible particle that all matter is made of.
330 BC Aristotle proposes the four element theory: earth, air, fire & water
360 BC Plato coins term ‘elements’ (stoicheia)
1605 Sir Francis Bacon published "The Proficience and Advancement of Learning" which contained a description of what would later be known as the scientific method.
1661 Robert Boyle published "The Sceptical Chymist" which was a treatise on the distinction between chemistry and alchemy. It also contained some of the earliest ideas of atoms, molecules, and chemical reaction marking the beginning of the history of modern chemistry
1754 Joseph Black isolated carbon dioxide, which he called "fixed air".
1778 Antoine Lavoisier wrote the first extensive list of elements containing 33 elements & distinguished between metals and non-metals 1766 Henry Cavendish discovered hydrogen as a colorless, odourless gas that burns and can form an explosive mixture with air
1773–1774 Carl Wilhelm Scheele and Joseph Priestly independently isolated oxygen
1803 John Dalton proposed "Dalton 's Law" describing the relationship between the components in a mixture of gases.
1828 Jakob Berzelius developed a table of atomic weights & introduced letters to symbolize elements 1828 Johann Dobereiner developed groups of 3 elements with similar properties 1864 John Newlands arranged the known elements in order of atomic weights & observed similarities between some elements 1864 Lothar Meyer develops an early version of the periodic table, with 28 elements organized by valence
1864 Dmitri Mendeleev produced a table based on atomic weights but arranged 'periodically ' with elements with similar properties under each other. His Periodic Table included the 66 known elements organized by atomic weights. 1894 William Ramsay discovered the Noble Gases.
1898 Marie and Pierre Curie isolated radium and polonium from pitchblende.
1900 Ernest Rutherford discovered the source of radioactivity as decaying atoms
1913 Henry Moseley determined the atomic number of each of the elements and modified the 'Periodic Law '.
1940 Edwin McMillan and Philip H. Abelson identify neptunium, the lightest and first synthesized transuranium element, found in the products of uranium fission.
1940 Glenn Seaborg synthesised transuranic elements (the elements after uranium in the periodic table

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Links: to the information http://chemistry.about.com www.history-timelines.org.uk