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The Periodic TableWho told the elements where to go?
First Elements, 1700’s
New Wave, 1800’s-Scientists used atomicspectroscopyto Identifying elementsusing uniqueline spectra.-Number of known elements doubled in less than 100 years.
Grouping ElementsJ.W. Dobereiner (1780-1849)-Found elements in groups of 3 that had similar properties.TRIADSExamples:Li, Na, KCa, Sr, BaCl, Br, I-Properties of the middle element were the average of thefirst and third elements.
Organizing the Elements1865 J.A.R. Newlands (1837-1898)-Now there were 62 known elements-Put in order of increasing atomicmass- Came up with the “Law of Octaves”“The properties of every eighth element waslike the first” (Just like in music)
There were some problems1)Foolish to relate to music2)Not all elements fit a patternin terms of chemicalproperties.3)Did not include Noble Gases(Most were not discoveredyet)
Slight Adjustment1869 Dmitri Mendeleev (1834-1907)-Wrote names of elements on cards with theproperties of each.-Also arranged periodic table in order of increasingatomic mass with exceptions:Te, ICo, NiThought they were miscalculated!
Mendeleev Cont.He also left some blanks on table to befilled in later and predicted properties(Ga, Ge, Sc)PropertyEkasiliconGermanium(disc. 1886)Atomic mass7272.59Density (g/cm3)5.55.35Melting Pt. (oC)High947ColorGrayGray
Henry Moseley(1887-1915)-Student of ErnestRutherford-Able to determine exactpositive charge of nucleus(Thus number of protons, oratomic number) using X-rays-Made a Periodic Table thatwas order by increasingatomic number
Periodic Law-When elements are arranged in order of increasing atomic number, theirphysical and chemical properties show a periodic pattern.-Period– Row going from left to right on the periodic table.-Family– column within the periodic table in which the elements exhibitsimilar properties.
Modern Periodic Table
Classifying ElementsMetals-Left side of periodic table (most elements are metals)-Good conductors of heat and electricity-Malleable (able to shape)-Ductile (able to be pulled into wire)-Have luster-Tend to lose electrons in chemical reactions (positivecharged ions)-Mercury is a liquid at room temperature,the restare solids
Classifying ElementsNonmetals-Upper right side of periodic table-Hydrogen is considered a nonmetal, but can behave like a metalsometimes.-Poor conductors-Tend to gain electrons in chemical reactions-Some are some are gases and some are solids-Bromine is a liquid nonmetal at room temperature.-Gases include: Hydrogen, nitrogen, oxygen, fluorine, helium,neon, argon, krypton, xenon, radon
ClassifyingElementsMetalloids or Semimetals-Found on the zig zag dividingline between metals andnonmetals.-B, Si, Ge, As, Sb, Te, Po-Can have properties ofmetals and nonmetals-Semiconductors are found inthis region.-Important for electronicstechnology!
Groups/FamiliesAlkali metals-Group IA-Highly reactive metals-Lose one electron to become1+ charge

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Term
Spring
Professor
Deeter,G
Tags
Atom, Periodic Table, Transition Metals, Ion, Chemical bond, Transition Metal Ionic Compound Name

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