6.1 Lewis Electron Dot Diagrams | Introductory Chemistry

Home » What Are Electron Dot Diagrams » 6.1 Lewis Electron Dot Diagrams | Introductory Chemistry

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Learning Objectives

By the end of this section, you will be able to:

  • Write Lewis symbols for neutral atoms and ions

Lewis Symbols of Monoatomic Elements

In almost all cases, chemical bonds are formed by interactions of valence electrons in atoms. To facilitate our understanding of how valence electrons interact, a simple way of representing those valence electrons would be useful.

A Lewis electron dot symbol (or electron dot diagram or a Lewis diagram or a Lewis structure) is a representation of the valence electrons of an atom that uses dots around the symbol of the element. The number of dots equals the number of valence electrons in the atom. These dots are arranged to the right and left and above and below the symbol, with no more than two dots on a side. (It does not matter what order the positions are used.)

For example, the Lewis electron dot symbol for calcium is simply

A Lewis structure of calcium is shown. A lone pair of electrons are shown to the right of the symbol.

Figure 1 shows the Lewis symbols for the elements of the third period of the periodic table.

A table is shown that has three columns and nine rows. The header row reads “Atoms,” “Electronic Configuration,” and “Lewis Symbol.” The first column contains the words “sodium,” “magnesium,” “aluminum,” “silicon,” “phosphorus,” “sulfur,” “chlorine,” and “argon.” The second column contains the symbols and numbers “[ N e ] 3 s superscript 2,” “[ N e ] 3 s superscript 2, 3 p superscript 1,” “[ N e ] 3 s superscript 2, 3 p superscript 2,” “[ N e ] 3 s superscript 2, 3 p superscript 3,” “[ N e ] 3 s superscript 2, 3 p superscript 4,” “[ N e ] 3 s superscript 2, 3 p superscript 5,” and “[ N e ] 3 s superscript 2, 3 p superscript 6.” The third column contains Lewis structures for N a with one dot, M g with two dots, A l with three dots, Si with four dots, P with five dots, S with six dots, C l with seven dots, and A r with eight dots.

Figure 1. Lewis symbols illustrating the number of valence electrons for each element in the third period of the periodic table.

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