Early Chemical Symbols symbols used by John Dalton
Early Chemical Symbols (symbols used by John Dalton)
Jöns Berzelius, (1779 -1848) n. Created symbols of the elements n. Capitalized first letter of name and included a second, lower case distinguishing letter if necessary
Combining Weight n. Determined the combining weights of all 43 known elements (1807 -1818) n. The weight of an element that combines with a fixed weight of another standard element. n. The standard that was used was ______.
Johann Döbereiner, (1780 -1849) n. Recognized triads (1829) n. Triad – a grouping of three elements that had similar physical and chemical properties.
Johann Döbereiner, (1780 -1849) n. Recognized that average of the highest and lowest combining weights of a triad equalled the combining weight of the middle element.
John Newlands, (1837 -1898) n. Law of Octaves which states that chemical and physical properties of the elements repeat with every eighth element when they are listed in order of increasing atomic weight. (1863)
Dmitri Mendeléev, (1834 -1907) n. Published the first Periodic Table of the Elements (1869) n. Table was based upon BOTH the properties and the atomic weights of the elements.
Mendeléev’s Periodic Law n. The properties of the elements are in periodic dependence on their atomic weights.
Mendeleev’s Genius Germanium (Ge) ekasilicon (Es) 72 Atomic Mass 72. 6 High Melting Point 968 o C 5. 5 g/ml Density 5. 36 g/ml Color gray K 2 Es. F 6 Obtained from K 2 Ge. F 6 Slightly Dissolves in HCl Does not dissolve Dark gray Es. O 2 4. 7 g/ml Oxide Form Density of oxide Ge. O 2 4. 70 g/m. L
Mendeleev’s Genius Germanium was discovered in 1886. Seventeen (17) years after the prediction of its existence
Changes in the Periodic Table since Mendeleev William Ramsay, (1852 -1916) • Discovered a new family for the periodic table which he called the noble gases. (1890’s) • Ramsay received the Nobel Prize in 1904 for his work on the noble gases.
Changes in the Periodic Table since Mendeleev Henry Moseley, (1887 -1915) • Determines the atomic numbers of the elements. (1913 -1914) • Reorders the periodic table.
Changes in the Periodic Table since Mendeleev The creation of larger elements by man-made means continues to extend the periodic table to present day
Modern Periodic Law: The physical and chemical properties of the elements are periodic functions of their atomic numbers.
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