Simple explanation of Reactivity Series
Metals can be arranged in a reactivity series based on the reactions of the metals and their compounds. The reactivity series lists elements (mostly metals) in order of decreasing reactivity. Understanding the reactivity series is fundamental to chemistry; it explains why most reactions happen and what changes the particles will undergo during the reaction. This is the order below (in decreasing reactivity):
- Potassium (K) - Most reactive
- Sodium (Na)
- Lithium (Li)
- Calcium (Ca)
- Magnesium (Mg)
- Aluminium (Al)
- Carbon (C)
- Zinc (Zn)
- Iron (Fe)
- Hydrogen (H)
- Copper (Cu)
- Silver (Ag)
- Gold (Au) - Least reactive
Reactions in the Reactivity Series
An example of a reaction:
Magnesium + copper(II) oxide → magnesium oxide + copper
This is called a displacement reaction. Displacement means that one of the elements has been pushed out of the compound it was in and replaced by a more reactive element (hence, displaced). All metals higher in the series will displace a metal lower than it from a compound. Look at the reactivity series. Copper is less reactive than magnesium, and so it has been displaced by magnesium to form magnesium oxide and copper. This reaction is irreversible, as copper isn’t reactive enough to be able to displace the magnesium.
Carbon is included in the series because carbon is used in the extraction of several metals from their ores (ores are usually metal oxides). If the metal being extracted is lower than carbon in the series, such as iron, the carbon will displace it and the result will be
Iron oxide + carbon → iron + carbon dioxide
2Fe2O3(s) + 3C(s) → 4Fe(l) + 3CO2(g)
Hydrogen is included in the series as many reactions of these metals, such as potassium, involve water and a hydroxide is formed. This will be further explained later on.
Magnesium + copper(II) oxide → magnesium oxide + copper
This is called a displacement reaction. Displacement means that one of the elements has been pushed out of the compound it was in and replaced by a more reactive element (hence, displaced). All metals higher in the series will displace a metal lower than it from a compound. Look at the reactivity series. Copper is less reactive than magnesium, and so it has been displaced by magnesium to form magnesium oxide and copper. This reaction is irreversible, as copper isn’t reactive enough to be able to displace the magnesium.
Carbon is included in the series because carbon is used in the extraction of several metals from their ores (ores are usually metal oxides). If the metal being extracted is lower than carbon in the series, such as iron, the carbon will displace it and the result will be
Iron oxide + carbon → iron + carbon dioxide
2Fe2O3(s) + 3C(s) → 4Fe(l) + 3CO2(g)
Hydrogen is included in the series as many reactions of these metals, such as potassium, involve water and a hydroxide is formed. This will be further explained later on.
