Redox: Oxidation and Reduction as Electron Transfer
Rewrite displacement and metal-with-acid reactions as electron transfer, where oxidation is loss of electrons and reduction is gain, and split a reaction into two half equations.
What a learner can do afterwards
- Names which species is oxidised and which is reduced in a displacement reaction
- Writes the two ionic half equations with electrons balanced
- Explains the reactivity series as an order of how readily a metal gives up electrons
- Relates the older gain-of-oxygen definition to the electron definition using the same reaction
1 · Read
Oxidation means losing electrons and reduction means gaining them. Remember it as OIL RIG: oxidation is loss, reduction is gain. The two always pair up, because every electron lost by one species is gained by another.
Drop zinc into copper sulfate solution and blue fades as copper coats the zinc. Zinc gives away two electrons, so zinc is oxidised. Copper ions take those electrons, so copper is reduced.
Split the reaction to see the swap. The oxidation half is zinc becoming zinc ions plus two electrons, and the reduction half is copper ions plus two electrons becoming copper. Balance atoms first, then balance charges with electrons.
Read the reactivity series as a giving order. A metal higher up gives up electrons more readily and pushes a lower metal out of its solution. The older oxygen definition still works: gaining oxygen is oxidation, and losing it is reduction.
Losers oxidise, gainers reduce, and half equations show the electron trade.
More to read
17.1 Balancing Oxidation-Reduction Reactions
Redox is electron trade. Oxidation loses electrons, reduction gains them; OIL RIG nails it. Split reactions into half equations to see the swap: zinc gives two electrons, copper ions take them. Balance atoms first, charges second. Every redox hides two halves. Find the giver and the taker.
17.2 Galvanic Cells
Batteries bottle redox. Zinc oxidises at one terminal, copper ions reduce at the other, and electrons march through wires as current. Salt bridges complete the circuit. Voltage measures the trade's eagerness. Rechargeables reverse the flow with mains power.
4.2 Classifying Chemical Reactions
Redox wears many costumes. Rusting steals iron's electrons for oxygen, bleaches swipe stains' electrons away, respiration cashes glucose electrons for ATP. Spot oxygen joins or hydrogen losses as clues, then confirm with electron counts.
2 · Watch
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Where it sits
Learn first
Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.