The number of valence electrons an element has can be determined by looking at the group number (vertical columns) of the element on the periodic table. For example, elements in Group 1 (alkali metals) have 1 valence electron, elements in Group 2 (alkaline earth metals) have 2 valence electrons, elements in Group 13 have 3 valence electrons, elements in Group 14 have 4 valence electrons, and so on. The exception to this trend is found in the transition metals in Groups 3-12, which have varying numbers of valence electrons.
