Topic 1 · 10.1–10.2 · Free
Topic Notes · Easy summaries with diagrams
Chapter 10 — chapter 10
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📘Easy summary
Oxidation is a process involving loss of electron or electrons (Fe²⁺ → Fe³⁺ + e⁻); reduction is a process involving gain of electron or electrons (Cu²⁺ + 2e⁻ → Cu). Both occur together in a redox reaction. Oxidation number is the apparent charge on an atom in a compound. Rules: free element = 0; monatomic ion = its charge; O usually −2 (−1 in peroxides); H +1 (−1 in metal hydrides); group 1 metals +1, group 2 +2; sum in a neutral compound = 0 and in an ion = its charge. Increase in oxidation number = oxidation; decrease = reduction.
⭐Key points
- Loss of e⁻ = oxidation; gain = reduction.
- Sum of O.N. = 0 or ion charge.
- O.N. up = oxidised.
🔬Diagram
🌿Real-life example
In K₂Cr₂O₇: 2(+1) + 2x + 7(−2) = 0 → x = +6.
💡Exam tip
- Write the sum equation for O.N. — it scores marks.
✅Quick check
1. O.N. of Mn in KMnO₄:
2. Gain of electrons is:
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