Molecular Structure
Lewis structures, the octet rule, and formal charge for building and evaluating molecules.
- Content level: CoreExpected foundation for a general high school chemistry audience.
- Content level: ChallengeEnrichment or more demanding reasoning within high school chemistry.
Content level is separate from question difficulty.
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Not assessed → Developing → Proficient → Mastered. Proficient requires 5 of the latest 6 different independent questions correct, plus independent success on 2 medium or hard questions. Mastered adds 2 new correct answers in mixed practice at least 24 hours later. Hints and retries remain useful practice, but do not establish proficiency. Review reminders do not lower a level.
Formal Charge
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Practice this topicLewis structures
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Practice this topicOctet rule
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Full lessons
Complete lessons with objectives, worked examples, quick checks, and linked practice.
- Valence Electrons and the Octet RuleOctet rule · 18 min
- Exceptions to the Octet RuleOctet rule · 20 min
- Drawing Lewis Structures Step by StepLewis structures · 22 min
- Multiple Bonds and Polyatomic IonsLewis structures · 20 min
- Resonance StructuresLewis structures · 20 min
- Formal Charge: Definition and CalculationFormal Charge · 20 min
- Choosing the Best Lewis Structure with Formal ChargeFormal Charge · 22 min
- Expanded Octets and Formal Charge Trade-offsFormal Charge · 22 min
Lessons
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