alleryStart learning →Which electrons leave first when an atom of a transition metal ionises?
AThe innermost core electrons
BThe outermost s electrons
CThe next to outer d electrons
DThe outermost f electrons
Answer & Solution
Correct answer: B. The outermost s electrons
1. Building up a transition metal configuration fills the s subshell before the d subshell.
2. Ionisation does not simply run that filling order backwards.
3. The outermost s electrons are the first to go, and only then may one or two d electrons follow.
4. That is why iron gives a two plus ion by losing its two outer s electrons before any d electron moves.
_Source: OpenStax Chemistry (CC BY 4.0), Ch 7 "Chemical Bonding and Molecular Geometry", section Electronic Structures of Cations_
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