Chemistry / Unit 12 Chem 2287 short lesson, about 20 seconds
Alkali Metal Reactivity Increases Down the Group
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The idea
Group 1 alkali metal reactivity increases down the group because atomic radius grows and ionization energy falls, making the single valence electron progressively easier to remove.
In practice
Cesium reacts more violently with water than sodium does, and sodium more violently than lithium.
Where people slip
Reactivity here means ease of oxidation, not physical hardness — the alkali metals actually grow softer, not tougher, down the group.
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