Group 1: The Alkali Metals

This lesson covers the properties, trends and reactions of the Group 1 elements (the alkali metals), as required by the Edexcel GCSE Combined Science specification (1SC0). You need to know their physical and chemical properties, how reactivity changes down the group, and the reactions of lithium, sodium and potassium with water and oxygen.

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The Group 1 Elements

The alkali metals are the elements in Group 1 of the periodic table. The ones you need to know for GCSE are:

Element	Symbol	Atomic Number	Electron Configuration
Lithium	Li	3	2, 1
Sodium	Na	11	2, 8, 1
Potassium	K	19	2, 8, 8, 1
Rubidium	Rb	37	2, 8, 18, 8, 1
Caesium	Cs	55	2, 8, 18, 18, 8, 1
Francium	Fr	87	(radioactive, very rare)

All Group 1 elements have one electron in their outer shell. This single outer electron is the key to understanding their chemistry.

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Physical Properties of Group 1 Metals