MYP Chemistry Reactivity Series Notes

Building the Reactivity Series from Observations

1. We can compare how different metals react with water, acids and oxygen.
2. From these observations, we can arrange metals from most reactive to least reactive.
3. This list is called the reactivity series.

Metal Reactions with Water

Metals show very different behaviours with water:

1. Very reactive metals (e.g. potassium, sodium, lithium, calcium):
   1. General equation (for Group 1 metals): $$2 \mathrm{M}(\mathrm{~s})+2 \mathrm{H}_2 \mathrm{O}(\mathrm{l}) \rightarrow 2 \mathrm{MOH}(\mathrm{aq})+\mathrm{H}_2(\mathrm{~g})$$
   2. React vigorously with cold water.
   3. Produce hydrogen gas and a metal hydroxide.
   4. Often produce heat and may ignite the hydrogen.
2. Moderately reactive metals (e.g. magnesium, zinc, iron):
   1. Little or no reaction with cold water.
   2. React with steam to form a metal oxide and hydrogen gas.
3. Unreactive metals (e.g. copper, silver, gold):
   1. Do not react with water or steam.

Metal Reactions with Acids

1. Metals can also be compared by how they react with dilute acids like HCl or H₂SO₄.
2. Metals above hydrogen in the reactivity series react with dilute acids to produce salt and hydrogen gas.
3. General equation: $$\text { Metal }+ \text { Acid } \rightarrow \text { Salt }+\mathrm{H}_2(\mathrm{~g})$$
4. Metals below hydrogen (e.g. copper, silver, gold) do not react with dilute acids at room temperature.

Metal Reactions with Oxygen

Most metals react with oxygen to form metal oxides, but at very different rates.

1. Highly reactive metals (e.g. potassium, sodium):
   1. React rapidly with oxygen in air.
   2. May need to be stored under oil to stop them reacting.
2. Moderately reactive metals (e.g. magnesium, iron):