How does Corrosion work

1) Metals can oxidise in air. Eg, sodium (very reactive) turns from shiny to dull, when cut or scratched: 4Na(s) + O2(g) → 2Na2O(s) 2) Other metals may oxidise more slowly. Gold and other very unreactive metals do not oxidise in air at all 3) Corrosion happens when a metal continues to oxidise. The metal becomes weaker over time and eventually all of it may become metal oxide 4) Rusting is an example of corrosion. It occurs when iron or steel reacts with oxygen and water