Chemistry / Unit 12 Chem 2281 short lesson, about 20 seconds
Classifying Elements by Orbital Filling
Captions available
The idea
An element is representative, transition, or inner transition based on whether its highest-energy electrons fill s/p, d, or f orbitals.
In practice
Sodium (3s) is representative, iron (3d) is transition, cerium (4f) is inner transition.
Where people slip
Group 12 finishes filling d orbitals early, so its last electron enters s, placing it with representative metals despite position.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
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