Electronic configurations and the periodic table
2 marks · HardAn unknown element X has the electronic configuration 2, 8, 3. State the group and period of element X in the Periodic Table.
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Group 3, Period 3
Also accept: Group III, Period 3; Group 3 and Period 3
Common mistakes: Mixing up group/period; Using the total number of electrons for the period
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Marking points
M1 · 1 mark · Identifies correct group from number of outer shell electrons (3)
M2 · 1 mark · States period from number of occupied shells (3)
Worked solution
Electronic configuration: 2, 8, 3 - Number of shells filled = 3, so Period = 3.
Number of electrons in outer shell = 3, so Group = 3 (or Group III).