Unit #1Unit #2Unit #3Unit #4Unit #5Unit #6Unit #7Unit #8Unit #9Unit #10
spacerUNIT # 3  

spacerof the Atom

spacerAtomic Number - Number of Protons
spacerNumber of Electrons
spacerMass Number - Number of Neutrons
spacer3.2 Isotopes
spacer3.3 Arrangement
spacerof Electrons

spacerThe Bohr Model
spacerBohr Diagram
spacerThe Lewis Electron-dot Symbol
spacerThe Quantum Mechanical Model of the Atom
spacerElectrons in the sublevels

spacer3.4 Electron

spacerFilling Order of the Sublevels

spacerElectron Configuration Notations
spacerElectron Configuration for Atoms of the First 20 Elements
spacerElectron Configuration and the Periodic Table
spacer3.5 Atomic Mass
spacerCalculation of Atomic Mass
spacerCalculate the Atomic Mass of Carbon

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3.4 - Electron Configurations of Atoms

3.4.1 - Filling Order of the Sublevels

How do we go about remembering the sequence in which electrons fill the sublevels?

The order in which electrons fill the sublevels is easy to remember if you follow these steps:
  1. Write the principal energy levels and their sublevels on separate lines (as shown on the diagram).
  2. Draw arrows over the sublevels (see the red diagonal lines on the diagram by placing your mouse over the diagram).
  3. Join the diagonal lines from end to end (click on the diagram to see how I have joined the red diagonal lines).
  1. Find the "start here" arrow and follow the arrows. The sublevels are magically arranged in the correct sequence from lowest energy (i.e. compare the order of filling sublevel sequence with the energy diagram of the sublevels).
  2. Click here to see the complete diagram

Section 4.8
Arrangement of Electrons in Sublevels ..p91




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