The arrangement of the electrons in an atom
2 marks · EasyAn atom of phosphorus has atomic number 15. Calculate and write its electronic configuration for the first 20 elements. Show your working.
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
2,8,5
Must show: Working shown, Correct final electronic configuration
Also accept: 2, 8, 5
Common mistakes: Splitting incorrectly (eg. 2,13); Not showing working
Show mark scheme and worked solution
Marking points
M1 · 1 mark · Shows working by filling shells: (2 in first shell, 8 in second, rest in third).
A1 · 1 mark · Correct electronic configuration: 2,8,5.
Worked solution
First shell: can hold 2 electrons.
Second shell: can hold up to 8. 15 - 2 = 13 left, 13 - 8 = 5 left for third shell.
Electronic configuration: 2,8,5