Find the element’s group number 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
Use the electron configuration to identify the highest principal energy level
Count the electrons in that highest energy level as valence electrons
For transition metals, check the outermost s electrons and sometimes d electrons
For ions, add electrons for negative charge and subtract electrons for positive charge
Confirm the total by comparing with the element’s position in the periodic table