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Unit 4: Organizing Atoms and Electrons—The Periodic Table


Unit Overview

As scientists discovered more and more chemical elements, they began developing systems to organize the elements by their chemical properties, leading to the modern periodic table. Through its organization, the periodic table makes clear the underlying chemical and physical trends among the elements. These characteristics—reactivity, atomic radius, electronegativity, and density—are linked to the distribution of electrons around the nucleus. The periodic table—undoubtedly the most important and useful document in chemistry—is being continually updated even today as scientists strive to create new manmade elements in laboratories.

by Louisa Morrison

Louisa Morrison


  1. Introduction
  2. History of the Periodic Table
  3. A Tour of the Periodic Table
  4. Atomic Mass, Atomic Number, and Carbon-12
  5. The Orbital Structure of the Atom
  6. Electron Configurations
  7. Effective Nuclear Charge and Size
  8. Ionization Energy and Ionic Radius
  9. Forming Compounds
  10. Electronegativity
  11. Naming Compounds
  12. Conclusion
  13. Further Reading

Download Unit 4 Online Text


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