atoms with eight electrons have full outer shells

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an example of an alternative conception:

Learners commonly think that, apart from in period 1 (where the electron shell is filled by two electrons), atoms have full outer shells with eight electrons.

This is the case for period 2, but not for period 3 (18 electrons in a full shell) and beyond.

Yet some elementary text books suggests that a full shell in period 3 would be eight electrons. If this were the case, many substances met in more advanced courses (e.g. PCl₅, many of the interhaolgrens such as IF₇) could not exist.

Indeed, some substances met in introductory courses, such as the sulphates and nitrates (and sulphuric and nitric acids) would not exist.

[Please be aware that a word may have different nuances, or even a different meaning, according to context.]« Back to Index