Group 1 — Alkali Metals

This lesson covers the properties and reactions of the Group 1 elements (alkali metals), as required by AQA GCSE Combined Science Trilogy (8464, Chemistry 4.1.2). Group 1 consists of lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs) and francium (Fr). You need to know their properties, reactions with water, and how reactivity changes down the group.

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Physical Properties of Group 1 Metals

Compared to most metals, the alkali metals are unusual:

Property	Group 1 Metals
Melting point	Relatively low for metals (and decreases down the group)
Density	Relatively low (Li, Na and K are less dense than water — they float)
Hardness	Very soft — can be cut with a knife
Appearance	Shiny when freshly cut, but tarnish rapidly in air

They are stored under oil to prevent them from reacting with oxygen and water vapour in the air.

Exam Tip: If asked "Why are alkali metals stored under oil?", answer: to prevent them from reacting with oxygen and moisture in the air. They are too reactive to be left exposed.

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