Unit #1Unit #2Unit #3Unit #4Unit #5Unit #6Unit #7Unit #8Unit #9Unit #10
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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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3.3 - Arrangement of Electrons

3.3.2 - The Lewis Electron-Dot Symbols of Elements

Gilbert N Lewis is widely known for his use of simple symbolic representations of elements that show valence electrons as dots. You've seen what the Bohr diagrams for the first 20 elements. Sometimes it is more convenient to represent the elements by its Lewis electron-dot symbol. It is not to say one is better than the other. The Bohr diagrams show arrangement of all the electrons.

The Lewis electron-dot symbols focus on the electrons in the highest principal energy level in the atom, the valence electrons. After all, these are the electrons that participate in chemical reactions. Lewis electron-dot symbols work well for the representative elements (see below and also section 4.2) . Take a look at the rules for writing Lewis electron-dot symbols.

The end result is, for representative elements belonging to:

Representative Elements in: Number of Valence Electrons
Group IA all elements have 1 valence electron
Group IIA all elements have 2 valence electrons
Group IIIA all elements have 3 valence electrons
Group IVA all elements have 4 valence electrons
Group VA all elements have 5 valence electrons
Group VIA all elements have 6 valence electrons
Group VIIA all elements have 7 valence electrons
Group VIIIA all elements have 8 valence electrons

In summary, view the Lewis electon-dot symbols for the representative elements belonging in the various groups.





Section 4.7
Electron-Dot Formulas of Elements ..p89




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