Group 1 — AQA GCSE Chemistry
Test yourself on Group 1 with AQA GCSE practice questions.
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Group 1 explained
Group 1 metals, the alkali metals, each have one electron in their outer shell.
Read the full explanation
That single outer electron is lost relatively easily when the metal reacts, forming a 1⁺ ion and giving the group its characteristic reactivity. Down the group, atomic radius increases and the outer electron is further from the nucleus and shielded by more inner shells, so the attraction holding it is weaker. Consequently reactivity increases down Group 1: lithium reacts steadily, sodium more vigorously, potassium vigorously enough to ignite, and rubidium and caesium are more reactive still. Melting points and boiling points decrease down the group because metallic bonding weakens as ions become larger and charge density falls. To predict properties, identify the trend from the data given, then extend it to the next element, justifying the prediction using outer-shell electron loss and increased atomic size.
Your focus
- Describe the outer-shell electron configuration of Group 1 atoms and the ion they form.
- Explain how distance from the nucleus and shielding affect the loss of the outer electron down Group 1.
- Use given trend data to predict a property of a Group 1 element and justify the prediction.
Group 1 exam tips
Marking Points
- State that Group 1 atoms each have one electron in their outer shell and lose it to form a 1⁺ ion.
- Explain that down the group the outer electron is in a shell further from the nucleus and is shielded by more inner shells, so less energy is needed to remove it.
- Link weaker attraction for the outer electron to increased reactivity down the group.
- Use given data, such as melting point or reaction observations, to identify a trend and predict a property of another Group 1 element.
- Justify a prediction by referring to atomic size, shielding and the ease of losing the outer electron.
- Describe observations such as fizzing, movement on water and flame colour as evidence of reactivity.
Examiner Tips
- 💡When asked to predict, quote the trend in the data first, then state the predicted value or behaviour for the named element.
- 💡Use the phrase outer electron throughout your explanation, because it keeps the answer focused on electronic structure.
- 💡For six-mark questions, structure your answer as electronic structure, then distance and shielding, then reactivity, then a prediction.
- 💡Check that any ion you write uses a superscript charge, for example Li⁺, not a baseline form.
Common Mistakes
- Saying reactivity decreases down Group 1 because atoms get bigger; correct this by explaining that the larger distance and extra shielding weaken the attraction for the outer electron, so reactivity increases.
- Confusing Group 1 with Group 7 trends; correct this by stating that Group 1 reactivity increases down the group whereas Group 7 reactivity decreases.
- Writing the ion as a baseline numeral with a postfix sign; correct this by using the superscript form such as Na⁺ and K⁺.
- Treating melting point and reactivity as following the same trend; correct this by noting that melting point decreases down Group 1 while reactivity increases.