Formal Charge Worksheet
A Grade 11 Chemistry worksheet focusing on understanding and calculating formal charges in molecules and polyatomic ions.
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Formal Charge Practice
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Read each question carefully and provide your answers in the spaces provided. Show all your work for calculations.
Formal charge is a concept used to determine the most plausible Lewis structure for a molecule or polyatomic ion. It is the hypothetical charge an atom would have if all bonds were perfectly covalent, meaning electrons in a bond are shared equally between the two atoms.
The formula for formal charge (FC) is:
FC = (Valence electrons) - (Non-bonding electrons) - (1/2 Bonding electrons)
1. Which of the following is the primary purpose of calculating formal charges?
To determine the oxidation state of an atom.
To identify the most stable Lewis structure.
To predict the polarity of a bond.
To determine the molecular geometry.
2. What is the formal charge of the oxygen atom in a water molecule (H₂O)?
-1
0
+1
+2
3. The sum of the formal charges in a neutral molecule must be .
4. Formal charge helps us distinguish between different structures of a molecule.
5. Calculate the formal charge for each atom in the carbon dioxide (CO₂) molecule. Show your work.
6. Draw the Lewis structure for the cyanide ion (CN⁻) and calculate the formal charge for both carbon and nitrogen atoms.
7. A Lewis structure with formal charges closest to zero on all atoms is generally the most stable.
True
False