The Lewis dot diagram for calcium is a visual representation of the element's valence electrons in the outer shell. It is symbolized by the abbreviation Ca with two dots around it, one for each of the two valence electrons.
An element can have up to eight valence electrons. The number of valence electrons in the outer shell helps determine where an element is located in the periodic table. Elements located in the first column have just a single valence electron, while elements in the second column have two. This pattern continues through the table until it reaches the final column of nonmetals with eight valence electrons.
In addition to single elements, Lewis dot diagrams are used for compounds. To complete one of these diagrams, the Lewis dot representations must first be determined for each element. Next, the most metallic or least electromagnetic element is placed in the center. In a compound, each element must satisfy the octet rule, meaning that it must have eight valence electrons. If any of the elements in the compound do not satisfy the octet rule, then they share electrons with another element. This sharing is represented by straight lines between the two elements. Valence electrons that aren't shared remain represented by dots.