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Group 2 atoms lose two outer electrons to form 2+ ions. Down the group, greater shielding and radius generally reduce the energy needed to remove those electrons, making oxidation easier. Metals react with oxygen to form oxides. Calcium and heavier Group 2 metals react readily with cold water to produce the hydroxide and hydrogen. Magnesium reacts slowly with cold water but more vigorously with steam to form magnesium oxide and hydrogen. State conditions because they change both observations and products.
Video by Eliot Rintoul. The video’s own board label is retained; follow the specification reference and scope notes on this lesson for assessed content.
Viewing focus: Explain Group 2 reactivity trends
After watching, attempt these questions before opening the answers. You can also use the written lesson below.
After watching 1: How does Group 2 hydroxide solubility generally change down the group?
It increases. More hydroxide can dissolve in a saturated solution.
After watching 2: What gas forms when calcium reacts with water?
Hydrogen. The metal displaces hydrogen from water.
What you'll be able to do
Group 2 atoms lose two outer electrons to form 2+ ions. Down the group, greater shielding and radius generally reduce the energy needed to remove those electrons, making oxidation easier. Metals react with oxygen to form oxides. Calcium and heavier Group 2 metals react readily with cold water to produce the hydroxide and hydrogen. Magnesium reacts slowly with cold water but more vigorously with steam to form magnesium oxide and hydrogen. State conditions because they change both observations and products.
Group 2 hydroxides generally become more soluble down the group, so their saturated solutions become more alkaline. Sulfates become less soluble down the group. Barium sulfate is very insoluble, allowing sulfate detection as a white precipitate after addition of acidified barium ions. Use a suitable acid that does not itself introduce sulfate. Distinguish solubility from rate: a slowly forming precipitate does not necessarily imply a larger equilibrium solubility.
Magnesium hydroxide is used to neutralise excess stomach acid; calcium hydroxide can treat acidic soil and neutralise acidic waste. These are acid–base reactions, not electron-transfer explanations. An insoluble sulfate used in an imaging context has different behaviour from soluble barium compounds. Explain an application using the particular substance and its properties rather than assuming every compound of one element behaves identically. When evaluating a practical, state precipitate colour, reagent order and the ionic equation that supports identification.
Attempt these problems on paper before opening the worked reasoning. Explain your steps as well as giving a final answer.
Common mistakes to avoid
Key takeaways
Question 1: How can aqueous sulfate be identified?
Ba2+(aq) + SO4²⁻(aq) → BaSO4(s).
Check the assessed scope and practical or mathematical requirements.
An external explanation or interactive activity to use alongside the lesson. It may include extension material.
Close the notes and answer from memory. Revisit any explanation you cannot yet reconstruct.
Test yourself
Answer a few questions, then review anything you missed.
Start with the quiz above to check the key ideas. You can also choose another topic from the practice library.