Find the element’s group on the periodic table
For main-group elements, use the group number to determine valence electrons
Group 1 elements have 1 valence electron
Group 2 elements have 2 valence electrons
Group 13 elements have 3 valence electrons
Group 14 elements have 4 valence electrons
Group 15 elements have 5 valence electrons
Group 16 elements have 6 valence electrons
Group 17 elements have 7 valence electrons
Group 18 elements have 8 valence electrons
Count the electrons in the outermost energy level for transition metals if needed
Use the electron configuration to identify the highest principal energy level
Count the electrons in that highest energy level as valence electrons
For ions, add electrons for negative charge
For ions, subtract electrons for positive charge