Chemistry / Unit 12 Chem 2299 short lesson, about 20 seconds
Twin: The Inert Pair Effect
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The idea
The inert pair effect is the tendency of heavier p-block elements to form a stable ion two below the group state, growing down a group and strongest in the heaviest member.
In practice
Thallium favors Tl+ over Tl3+; lighter neighbor indium shows In+ alongside In3+, less dominantly.
Where people slip
Assuming this lowered state appears only in the heaviest member misses mid-group cases like tin and indium.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
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