Electronic configurations and the periodic table
4 marks · NormalDraw or describe the electronic configuration for sodium (Na, atomic number 11).
Identify its group and period in the Periodic Table.
Explain how sodium’s position in the Periodic Table is related to its electronic configuration.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
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(a) 2,8,1
(b) Group 1, Period 3
(c) Group number is the number of outer shell electrons (1), period is the number of shells (3). Sodium’s electronic configuration shows it has 3 shells, with 1 electron in the outer shell.
Common mistakes: Counting only the first two shells
Show mark scheme and worked solution
Marking points
A1 (a) · 1 mark · Correctly gives configuration as 2,8,1
A2 (b) · 1 mark · Correct group and period stated: group 1, period 3
M1 (c) · 1 mark · Links group to outer electrons
M2 (c) · 1 mark · Links period to number of shells
Worked solution
a) Sodium atomic number 11: 2,8,1
b) Group 1 (1 outer electron), Period 3 (3 shells)
c) Group number = outer electrons, period number = shells — matches configuration.