Extracting metals and equilibria Study Guide

The reactivity series arranges metals based on their tendency to lose electrons and form positive ions. A metal's position in this series directly relates to its resistance to oxidation, which is the process of losing electrons and reacting with oxygen or other non-metals. Metals higher up in the reactivity series readily lose electrons, making them more reactive and less resistant to oxidation. For example, alkali metals like sodium and potassium are highly reactive and oxidise very easily, even reacting explosively with water and oxygen in the air. Conversely, metals lower down in the series, such as gold and platinum, have a weaker tendency to lose electrons. This makes them less reactive and highly resistant to oxidation. They are often referred to as 'noble' metals because they do not readily corrode or tarnish. The reactivity series provides a predictable order for how metals will behave when exposed to oxidising agents, with more reactive metals displacing less reactive ones from their compounds.

Oxidation and reduction are fundamental chemical processes often observed in reactions involving oxygen. Oxidation is defined as the gain of oxygen by a substance. For example, when a metal like iron rusts, it combines with oxygen to form iron oxide, which is an oxidation reaction. Conversely, reduction is defined as the loss of oxygen from a substance. A common example is the extraction of metals from their ores, where metal oxides are heated with carbon to remove the oxygen, leaving the pure metal. These processes always occur simultaneously; if one substance gains oxygen (is oxidised), another substance must lose oxygen (is reduced) in what is known as a redox reaction.