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HISTORY OF THE PERIODIC TABLE I GREEKS (400 B.C.) – used the words “element” and “atom”. II Antoine Lavoisier (1700’s) – divided the element into 4 Classes III Dobereiner (1800’s) – noted the similar elements often had relative atomic masses A.E. Beguyer de Chancourtois – created a cylindrical table of elements to display the periodic reoccurrence of properties IV Cannizaro – determined atomic weights for 60 or so elements V John Newlands – arranged the table with the elements given a serial number in order of atomic weight - made evident “eighth element, starting from a given one, is a kind of repetition of the first” (Law of Octaves) VI DMITRI MENDELEEV(Mendeleyev) – published his periodic table & law (1869) – forecast the properties of missing elements VII “MODERN PERIODIC TABLE” – arranged according to size of the atomic weight but with group 0 added by Ramsay MOSELY – reordered the table according to atomic numbers (nuclear charge) rather than weight. VIII HARRY HUBBARD (1924) published the modernized Medeleyev’s periodic table called “Periodic Chart of the Atoms” IX 1930 Glenn Seaborg – “plucked out” the heaviest Elements (Actinide series & Lanthanide series) X ROY ALEXANDER – designed a three-dimensional Periodic chart (1994) retains the separate Lanthanide and Actinide series. HOW DOES THE PERIODIC TABLE LOOK LIKE? I GROUP/FAMILY – vertical columns - have similar chemical properties Group 1A – Alkali Metals (soft, malleable; lustrous, good conductors, MOST REACTIVE family of metals) Group 2A – Alkaline Earth (higher densities and melting points than alkali metals; not as reactive as alkali) Group 7A – Halogens ( MOST REACTIVE Non-Metals; do not occur free in nature; commonly found in sea water, minerals, & living tissues) Group 8A – Noble gases (VERY INACTIVE elements, used in balloons, scuba diving tanks, light bulbs) II PERIODS – horizontal row