SaitechAI Worksheet – Formal Charges in Chemistry
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1. Calculate the formal charge of oxygen in the hydroxide ion (OH⁻).
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Key: O has 6 valence e⁻; nonbonding=6, bonding=2 → FC = 6 – 6 – (2/2) = -1.
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2. Find the formal charge of nitrogen in ammonium ion (NH₄⁺).
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Key: N valence=5; nonbonding=0, bonding=8 → FC=5 – 0 – (8/2) = +1.
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3. Calculate the formal charge on central C atom in CO₂.
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Key: C valence=4; nonbonding=0; bonding=8 → FC=4 – 0 – 4=0.
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4. Find formal charge of oxygen in H₃O⁺ ion.
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Key: O valence=6; nonbonding=2; bonding=6 → FC=6 – 2 – 3=+1.
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5. Find formal charge of each O in O₃ (ozone).
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Key: Resonance forms → terminal O: -1 and 0; central O: +1.
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6. Calculate formal charge of nitrogen in NO₃⁻ ion.
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Key: N valence=5; nonbonding=0; bonding=8 → FC=5 – 0 – 4=+1.
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7. Calculate formal charge of chlorine in ClO₄⁻ ion.
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Key: Cl valence=7; bonding=8; FC=7 – 0 – 4=+3 (resonance spread).
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8. Find formal charge of carbon in CN⁻ ion.
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Key: C valence=4; nonbonding=2; bonding=6 → FC=4 – 2 – 3=-1.
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9. Find formal charge of nitrogen in NO₂⁻ ion.
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Key: N valence=5; bonding=7; nonbonding=0 → FC=5 – 0 – 3.5=+1.5 (delocalized).
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10. Calculate formal charge of phosphorus in phosphate ion (PO₄³⁻).
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Key: P valence=5; bonding=8; nonbonding=0 → FC=5 – 0 – 4=+1.
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Total Score: 0 / 20