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Topic Notes · Easy summaries with diagrams
Chapter 3 — Chapter 3 — Chemical Bonding
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📘Easy summary
Atoms combine to lower their energy and gain stability. Noble gases are unreactive because helium has 2 and others have 8 electrons in the outermost shell. Hence the duplet rule (2 electrons for H, He) and octet rule (8 electrons).
⭐Key points
- Na easily loses 1 electron rather than gaining 7.
- H can lose 1 e⁻ (H⁺) or gain 1 e⁻ (hydride H⁻, completes duplet).
- Alkali and alkaline earth metals are electropositive; they bond with electronegative O and Cl.
- Later investigations found the octet rule less important.
🔬Diagram
🌿Real-life example
Na (2,8,1) → Na⁺ (2,8) like neon.
💡Exam tip
- Only outermost-shell electrons take part in bonding.
✅Quick check
1. Helium is stable due to:
2. Atoms bond to:
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