Valence electrons
Valence electrons are the electrons in the outer shell of an atom. They help explain why many elements form predictable ions.
Periodic Table Valence Charges
Valence charges is a common search phrase for the charge patterns students learn from the periodic table. In chemistry, it is more precise to separate valence electrons, common ionic charges, and oxidation states.
Quick answer: main-group ion charges often follow the group pattern, such as Group 1 as +1, Group 2 as +2, Group 16 as -2, and Group 17 as -1. Transition metals need compound-specific checking.
Valence charges vs ionic charges
Ionic charge
Ionic charge is the real electrical charge on an ion, such as Na+, Mg2+, O2-, or Cl-.
Oxidation state
Oxidation state is a bookkeeping value inside compounds. It often matches ionic charge in simple salts, but not always.
Main-group pattern
Charges of elements on the periodic table
Use this as a starting pattern, then check exceptions.
| Periodic table group | Common ionic charge | Example ions | How to read it |
|---|---|---|---|
| Group 1 | +1 | Li+, Na+, K+ | Alkali metals usually lose one electron. |
| Group 2 | +2 | Mg2+, Ca2+, Ba2+ | Alkaline earth metals usually lose two electrons. |
| Group 13 | +3 | Al3+ | Aluminum is the most common classroom example. |
| Group 15 | -3 | N3-, P3- | Also has positive oxidation states in some compounds. |
| Group 16 | -2 | O2-, S2-, Se2- | Oxide, sulfide, and selenide ions use this pattern. |
| Group 17 | -1 | F-, Cl-, Br-, I- | Halides usually form 1- ions in binary salts. |
How to use valence charge patterns
Start with the group
For main-group elements, use the periodic table group to predict the common simple ion charge.
Check the element page
Use element pages for specific cases such as selenium charge, oxygen charge, and sodium charge.
Be careful with metals
Lead, copper, iron, mercury, tin, and many transition metals can have more than one common charge.
FAQ
Are valence charges and ionic charges the same?
Not exactly. Valence electrons describe outer-shell electrons, ionic charge is the actual charge on an ion, and oxidation state is a bookkeeping value used in compounds.
Why do students search for valence charges?
Many classroom lessons use valence electrons to predict common ion charges, so students often use the phrase valence charge when they mean common ionic charge.
Do transition metals follow the same valence charge pattern?
No. Transition metals can form more than one positive ion, so use the Roman numeral in the compound name or solve from the formula.
Related charge pages
Periodic table with chargesMain table for common element charges.Periodic table with ionic chargesIonic-charge focused support page.Common ion chargesMonatomic and polyatomic ion charges.Transition metal chargesRoman numerals and variable metal charges.Ionic compound calculatorBalance positive and negative charges into formulas.Lead chargePb2+ and Pb4+ explained with examples.