# Describe the trends in melting point and reactivity as you go down Group 0 (the noble gases) and Group 1 (the alkali metals) of the periodic table, and explain why the reactivity trends in these two groups are different from each other.

> Edexcel A-Level Chemistry (9CH0) — 1.2 Periodic table and trends · Describe · 5 marks

> Group 0 elements are unreactive gases used in lighting and welding. Group 1 elements are highly reactive metals stored under oil to prevent reaction with air and water.

## Mark scheme (5 marks)

1. Melting point increases going down Group 0 (noble gases)
2. Group 0 elements are unreactive / do not react because they have a full outer shell of electrons
3. Reactivity increases going down Group 1 (alkali metals)
4. Going down Group 1, the outer electron is lost more easily because it is further from the nucleus / there is more shielding from inner electron shells
5. The trends are different because Group 0 elements have a full outer shell so never need to gain or lose electrons, whereas Group 1 elements have one electron in their outer shell which they lose to react, and this becomes easier down the group

## Key terms

- [Group 0](https://www.gradenine.co.uk/glossary/group-0)
- [Group 1](https://www.gradenine.co.uk/glossary/group-1)
- [reactivity](https://www.gradenine.co.uk/glossary/reactivity)

## Related

- [Revision notes for Edexcel A-Level Chemistry (9CH0)](https://www.gradenine.co.uk/learn)
- [How to answer "Describe" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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