Na2O
sodium oxygen compound
Sodium ions can balance O2- in simple ionic examples.
What Is the Charge of Oxygen?
Oxygen commonly forms O2- in introductory ionic compounds.
Quick answer: Oxygen usually has a common ionic charge of -2, written as O2-.
| Element | Oxygen |
|---|---|
| Symbol | O |
| Atomic number | 8 |
| Common ionic charge | -2 |
| Common ions | O2- |
Why Oxygen has this charge
Oxygen has common reference charges of -2. Use the compound name and context to distinguish ionic charge from oxidation state.
Oxygen charge examples
CaO
calcium oxygen compound
Calcium ions can balance common negative Oxygen ions.
FAQ
Is Oxygen charge the same as oxidation state?
Ionic charge is the charge on an actual ion. Oxidation state is a bookkeeping number used inside compounds. They can match, but they are not always the same thing.
How do I use this in formulas?
Combine positive and negative ions so the total charge is zero. You can also use the ionic compound calculator.
Where can I see the full chart?
Use the periodic table with charges or the ionic charges chart.