CHAPTER 5 The Periodic Table

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CHAPTER 5 The Periodic Table
Lecture
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Original Production
Time
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Section 5.1 Organizing the Elements
Meet Antoine Lavoisier a French chemist that in
1789 first grouped the known elements into
categories that made sense metals, non-metals,
gases, and earths.
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This classification scheme lasted for 80 years
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Then along comes a Russian fellow by the name of
Dmitri Mendeleev
Like my hat?
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I play spider solitaire like nobodys business
Im a party animal
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• Mendeleevs Proposal
• he arranged the elements into rows in order of
  increasing mass so that elements with similar
  properties were in the same column
• now known as a periodic table an arrangement of
  elements in columns, based on a set of properties
  that repeat from row to row
• his periodic table was published in 1872

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• How is the table organized?

2. What do the long dashes represent?
3. Why are masses listed with some of the dashes,
but not all of them?
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• Mendeleevs Prediction
• left blanks in periodic table (unknowns)
• predicted the gaps would be filled when more
  elements were discovered
• predicted the gap under Aluminum would be a soft
  metal, with a low melting point and a density of
  5.9g/cm3
• 1st to offer an explanation of how the
  properties of an element were related to its
  location in his table

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• Evidence Supporting Mendeleevs Table
• 1875 French discover Gallium (Ga) melting point
  of 29.7oC and a density of 5.91 g/cm3
• 1879 discovery of Scandium (Sc)
• 1886 discovery of Germanium (Ge)
• the close match between Mendeleevs predictions
  and the actual properties of new elements showed
  how useful his periodic table could be

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