Drawing diagrams of electronic configurations
3 marks · EasyAnswer the following questions about electron shells:
State the maximum number of electrons that the second shell can hold.
Describe the order in which electrons fill the first, second and third shells.
Explain why electrons do not start to fill the third shell before the second shell is full.
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.
Show answer
(a) 8
(b) First shell fills first, then second, then third.
(c) Because each shell must be full before electrons go into the next shell (lower energy shells fill first).
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · States maximum in second shell is 8 electrons.
B1 (b) · 1 mark · Describes correct order: first, then second, then third shell.
B1 (c) · 1 mark · Explains that shells must be filled in order/lower shells first/full before next.
Worked solution
a) Second shell can hold 8 electrons.
b) Electrons fill the first shell first, then the second shell, and then the third shell.
c) Electrons do not start to fill the third shell before the second is full because lower energy shells fill first (must be filled before moving to the next shell).