Electronic configurations and the periodic table
2 marks · EasyExplain why all elements in Group 7 have seven electrons in their outer shell.
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Also accept: The group number for Groups 1–7 equals the number of outer shell electrons.
Common mistakes: Confusing period and group roles; Saying 'it is a rule' without further explanation
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Marking points
M1 · 1 mark · States or explains the pattern/rule linking group number to outer shell electrons for Groups 1–7.
A1 · 1 mark · Applies correctly, stating that Group 7 elements each have seven electrons in the outer shell.
Worked solution
For Groups 1–7, the group number equals the number of electrons in the outer shell. So, every element in Group 7 has seven outer electrons.