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THE PERIODIC TABLE. HISTORY. Late 18 th century: Lavoisier's list of 28 elements Early 19 th century: John Dalton's list of approximately 60 elements Döbereiner's "triads" of elements with related or similar properties; e.g., Ca, Sr and Ba
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Late 18th century: Lavoisier's list of 28 elements • Early 19th century: John Dalton's list of approximately 60 elements • Döbereiner's "triads" of elements with related or similar properties; e.g., Ca, Sr and Ba • John Newlands "octaves" or groups of eight elements after which properties seemed to repeat Early History
(Julius) LotharMeyer (1830 – 1895) German chemist who, independently of Dmitri Mendeleev, developed a periodic classification of the chemical elements. Though originally educated as a physician, he was chiefly interested in chemistry and physics.
Began working on his periodic table of the elements in the late 1860s. • Arranged the known 63 elements by their atomic weights and organized them into groups possessing similar properties. • Where there were gaps, he correctly predicted the properties for the undiscovered elements (gallium, scandium and germanium). DIMITRIMENDELEEV (1834-1907)
Henry Moseley (1887-1915) • Established the concept of atomic numbers. • Showed that the ordering of the wavelengths of the x-ray emissions of the elements coincided with the ordering of the elements by atomic number(1913). • Developed periodic table based on atomic number.
PERIODIC LAW PROPERTIES OF ELEMENTS ARE PERIODIC FUNCTIONS OF THEIR ATOMIC NUMBERS
GLENN SEABORG (1912-1999) • starting with plutonium in 1940, he discovered all the transuranium elements from 94 to 102 • reconfigured the periodic table by placing the actinide series below the lanthanide series • in 1951, Seaborg was awarded the Nobel Prize in chemistry for his work. Element 106 has been named seaborgium (Sg) in his honor.
Properties of Major Divisions Metals • lusterous, shiny • typically solids at room temperature (except Hg, Cs) • good conductors of heat and electricity • malleable and ductile • tend to lose electrons easily (form cations)
Properties of Major Divisions Nonmetals • do not have a metallic luster • poor conductors of heat and electricity • may be solid, liquid or gas at room temperature (majority are gases) • non malleable, non ductile • tend to gain electrons easily (form anions)
Properties of Major Divisions Semi-metals (metalloids) have properties that are intermediate between metals and nonmetals.
Elmsley, John, The Elements,3rd Ed., Clarendon Press, Oxford,1998.Chemistry: Connections to Our Changing World, LeMay, et al., Prentice Hall, 1996.http://www.britannica.com/bcom/eb/article/5/0,5716,53705+1+52397,00.htmlhttp://www.crosswinds.net/~smarsden/unit04/l6u4.htmhttp://www.thirteen.org/archive/hawking/cosmostar/html/cstars_mendel.htmlhttp://www.sweethaven.com/chemele/pertab01.html BIBLIOGRAPHY