Tags: atomic structure, periodic table
Categories: Alternative conceptions
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.
