# Explain why elements in the same group of the periodic table have similar chemical properties, and describe how the reactivity of Group 1 metals changes as you go down the group.

> OCR A-Level Chemistry B: Salters (H433) — 3.1 The periodic table and periodicity · Explain · 5 marks

> The periodic table arranges all known elements in order of increasing atomic number. Elements in the same group share certain characteristics that make them behave in chemically similar ways.

## Mark scheme (5 marks)

1. Elements in the same group have the same number of electrons in their outer shell
2. The number of outer shell electrons determines how an element reacts / what type of bonds it forms
3. Reactivity of Group 1 metals increases going down the group
4. As you go down Group 1, the outer electron is in a shell that is further from the nucleus
5. The outer electron is lost more easily because the attraction between the nucleus and the outer electron decreases / the outer electron is less strongly held

## Key terms

- [group](https://www.gradenine.co.uk/glossary/group)
- [reactivity](https://www.gradenine.co.uk/glossary/reactivity)
- [periodic table](https://www.gradenine.co.uk/glossary/periodic-table)

## Related

- [Revision notes for OCR A-Level Chemistry B: Salters (H433)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" 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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