Formal Charge Formula:
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Definition: Formal Charge is the charge assigned to an atom in a molecule, assuming that electrons in all chemical bonds are shared equally between atoms, regardless of relative electronegativity.
Purpose: It helps determine the most stable Lewis structure of a molecule and predict molecular reactivity.
The calculator uses the formula:
Where:
Explanation: The formula compares the number of valence electrons in the free atom to the number of electrons assigned to the atom in the Lewis structure.
Details: Formal charges help identify the most plausible Lewis structure when several are possible. Structures with formal charges closest to zero are typically more stable.
Tips: Enter the number of valence electrons, bonding pair electrons, and non-bonding pair electrons. All values must be ≥ 0.
Q1: What does a formal charge of zero mean?
A: A formal charge of zero suggests the atom has exactly half of the bonding electrons and all of its non-bonding electrons.
Q2: Can formal charge be fractional?
A: While the calculation might result in a fraction, formal charge is typically reported as a whole number in chemical structures.
Q3: What's the ideal formal charge for stability?
A: Structures with formal charges closest to zero are generally more stable. Large formal charges indicate less stable configurations.
Q4: How do I find valence electrons?
A: Valence electrons can be determined from an element's group number in the periodic table.
Q5: Does formal charge equal actual charge?
A: No, formal charge is a bookkeeping concept. Actual charge distribution may differ due to electronegativity differences.