The arrangement of the electrons in an atom
4 marks · NormalThe following table shows information about three elements:
| Element | Atomic number |
|---|---|
| Sulfur | 16 |
| Phosphorus | 15 |
| Oxygen | 8 |
Use this information to answer the following questions.
State the number of electrons in an atom of phosphorus.
Write the electronic configuration of oxygen.
Write the electronic configuration of sulfur.
State the number of electrons in the outer shell of a sulfur atom.
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) 15
(b) 2,6
(c) 2,8,6
(d) 6
Also accept: Accept electron configurations as numbers with spaces or commas.
Common mistakes: Incorrect shell order; Counting electrons incorrectly
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · States the number of electrons in phosphorus as 15.
B1 (b) · 1 mark · Gives the correct electronic configuration of oxygen (2,6 or 2 6).
B1 (c) · 1 mark · Gives the correct electronic configuration of sulfur (2,8,6 or 2 8 6).
B1 (d) · 1 mark · States the number of outer shell electrons in sulfur as 6.
Worked solution
a. Phosphorus has atomic number 15, so it has 15 electrons.
b. Oxygen (atomic number 8) has electron configuration 2,6.
c. Sulfur (atomic number 16) has electron configuration 2,8,6.
d. The outer shell of sulfur contains 6 electrons.