Chapter 4: The Periodic Table

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04 Chapter.ppt - The Nature of Matter

Chapter 4: The Periodic Table

Table of Contents
Section 1: Introduction to the
Periodic Table
Section 2: Representative Elements Section 3: Transition Elements

Development of the Periodic Table: Mendeleev’s Table of Elements

  • A Russian chemist, Dmitri Mendeleev, published his first version of his periodic table in the Journal of the Russian Chemical Society in 1869.
  • When Mendeleev arranged the elements in order of increasing atomic mass, he began to see a pattern.
  • Elements with similar properties fell into groups on the table.

Section 1: Introduction to the Periodic Table
  • To make his table work, Mendeleev had to leave three gaps for missing elements.
  • Based on the groupings in his table, he predicted the properties for the missing elements.
  • Within 15 years, all three elements—gallium, scandium, and germanium

  • —were discovered.

Moseley’s Contribution

  • Although Mendeleev’s table correctly organized most of the elements, a few elements seemed out of place.
  • In the early twentieth century, the English physicist Henry Moseley realized that Mendeleev’s table could be improved by arranging the elements according to atomic number rather than atomic mass.

Today’s Periodic Table

  • In the modern periodic table, the elements still are organized by increasing atomic number.
  • The rows or periods are labeled 1-7.
  • A period is a row of elements in the periodic table whose properties change gradually and predictably.

Today’s Periodic Table

Today’s Periodic Table

  • The periodic table has 18 columns of elements.
  • Each column contains a group, or family, of elements.
  • A group contains elements that have similar physical or chemical properties.

Zones on the Periodic Table

  • The periodic table can be divided into sections.
  • One section consists of the first two groups, Groups 1 and 2, and the elements in Groups 13-18.

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