electron shell
Pronunciation
Noun
B2 Upper-intermediate
Quick answer
One of the regions around an atomic nucleus where electrons are arranged, each holding a limited number of electrons.
Usage notes
Electron shells fill up in a set order, and it's the outermost, incomplete shell that mostly determines an atom's chemistry.
Test yourself
Which word fits the gap? "Sodium has one electron in its outermost _____, which is why it so readily forms a plus one ion."
Answer: electron shell
In your own words, what does "electron shell" mean?
One of the regions around an atomic nucleus where electrons are arranged, each holding a limited number of electrons.
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