Most metals are extracted from ores found in the Earth's crust.
Unreactive metals are found in the Earth's crust as uncombined elements.
Oxidation is the gain of oxygen.
Reduction is the loss of oxygen.
The reactivity series was formed based on the reactivity of the metals with water and dilute acids, and that these reactions show the relativetendency of metal atoms to form carbons.
A metal's relative resistance to oxidation is related to its position in the reactivity series.
REDOX is oxidation and reduction happening at the same time.