Introduction to Mendeleev

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Introduction to MendeleevsPeriodic Table of
Elements

• Contemporary Chemistry
• Mrs. Coyle

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The Elements Song by Tom Lehrer

• http//www.privatehand.com/flash/elements.html

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Organizing Information

• What criteria can be used?
• Activity Organizing Cards

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How are days organized?
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Dobereiners Triads (Germany, 1829)

• J.W. Dobereiner organized some elements into some
  groups of 3.
• He used similarities in chemical properties.
• Example The halogens chlorine, bromine and
  iodine.
• Atomic Mass(u)
• Cl 35.453
• Br 79.904 I
  126.904

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Dmitri MendeleevRussian1860s
The Person Who Organized the Elements
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Mendeleev

• Teacher at St. Petersburg University.
• Was working on a textbook for his Chemistry
  students.
• He organized the 63 elements known at the time.

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His Criteria

• Increasing atomic mass.
• Physical and Chemical Properties.

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Sodiums Reaction with H2O
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Potassiums Reaction with H2O
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Periodicity

• Reoccurrence (repetition) of properties at
  regular intervals.

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Mendeleevs Periodic Table
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Like A Calendar
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Mendeleevs Predictions

• He left spaces on the table for undiscovered
  elements.
• He predicted the properties of elements that had
  not yet been discovered.
• How?

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Example Eka-aluminum

• He placed this undiscovered element below
  aluminum.
• He predicted the melting point to be low and the
  density to be 5.9g/cm3.
• It was later found and named Gallium with a
  density of 5.91g/cm3 and melting point of 29.7oC.

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Gallium
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A brief comparison of the modern periodic table
to Mendeleevs

• What is the main criterion used to organize
  elements in the modern periodic table?

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Recap

• Mendeleevs Criteria
• Periodicity
• Prediction