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To keep track of valence electrons, a system of symbols, called Lewis symbols was designed.
To draw a Lewis symbol, write its chemical symbol surrounded by dots representing its valence electrons.
For example, lithium is written like this because it has one valence electron:
Actually, all the group IA elements have one valence electron and therefore also have one dot surrounding their symbol.
The lewis symbols for all eight A-group elements of period 2 are:
Similarly, all IA elements have one dot, IIA elements have two dots, IIIA elements have three dots, and so forth.
The group number is equal to the number of valence electrons in representative elements.
Lewis symbols are used mostly for showing covalent bonds, but can be used to describe what happens during ion formation.
For example, here is the formation of NaCl: