Uploaded August 2025 | Updated September 2026, 2 weeks ago
Writing Ionic Formulas
Dr. DeBacco
1. Identify the Ions
Determine the cation (positive ion) and anion (negative ion).
Example: Sodium (Na⁺) and Chloride (Cl⁻)
2. Determine the Charges
Use the periodic table or ion chart to find the typical charges.
Example: Calcium (Ca²⁺) and Nitrate (NO₃⁻)
3. Balance the Charges
Total positive charge must balance total negative charge.
You may need multiple ions to achieve balance.
Example: Ca²⁺ + 2(NO₃⁻) → Ca(NO₃)₂
4. Write the Formula
Start with the cation, then the anion.
Use subscripts to show how many ions are needed.
Don’t show charges in the final formula—just the correct ratio.
Example: Aluminum (Al³⁺) and Oxygen (O²⁻) → Al₂O₃
Tips
Transition metals might have multiple charges Roman numerals can help
Fe²⁺ = iron(II)
Polyatomic ions like SO₄²⁻ or NH₄⁺ should be kept in parentheses if you need more than one.
Example: Mg²⁺ and SO₄²⁻ → MgSO₄
But Mg²⁺ and two NO₃⁻ → Mg(NO₃)₂
Link to Lecture Slides: drive.google.com/file/d/1hfpSqcfTnEa7yziX1-0bQbDQnu6Ngubj/view?usp=drive_link
*Due to the description character limit the full work cited for "Writing Ionic Formulas" can be viewed at... docs.google.com/document/d/1Ma3vDciR70ybAiAD_q_gjprwI1zwY8Qy/edit?usp=drive_link&ouid=104237452697237972847&rtpof=true&sd=true
Writing Ionic Formulas
Dr. DeBacco
1. Identify the Ions
Determine the cation (positive ion) and anion (negative ion).
Example: Sodium (Na⁺) and Chloride (Cl⁻)
2. Determine the Charges
Use the periodic table or ion chart to find the typical charges.
Example: Calcium (Ca²⁺) and Nitrate (NO₃⁻)
3. Balance the Charges
Total positive charge must balance total negative charge.
You may need multiple ions to achieve balance.
Example: Ca²⁺ + 2(NO₃⁻) → Ca(NO₃)₂
4. Write the Formula
Start with the cation, then the anion.
Use subscripts to show how many ions are needed.
Don’t show charges in the final formula—just the correct ratio.
Example: Aluminum (Al³⁺) and Oxygen (O²⁻) → Al₂O₃
Tips
Transition metals might have multiple charges Roman numerals can help
Fe²⁺ = iron(II)
Polyatomic ions like SO₄²⁻ or NH₄⁺ should be kept in parentheses if you need more than one.
Example: Mg²⁺ and SO₄²⁻ → MgSO₄
But Mg²⁺ and two NO₃⁻ → Mg(NO₃)₂
Link to Lecture Slides: drive.google.com/file/d/1hfpSqcfTnEa7yziX1-0bQbDQnu6Ngubj/view?usp=drive_link
*Due to the description character limit the full work cited for "Writing Ionic Formulas" can be viewed at... docs.google.com/document/d/1Ma3vDciR70ybAiAD_q_gjprwI1zwY8Qy/edit?usp=drive_link&ouid=104237452697237972847&rtpof=true&sd=true
