The Periodic Table
7 marks · HardThis question is about electronic configurations and differences in electrical conductivity between metals and non-metals.
Draw a diagram to show the electronic configuration of the element with atomic number 6. Use shells and electrons as dots or crosses.
Element X has the electronic configuration 2,8,1. Identify whether X is a metal or a non-metal. Explain your answer based on its electronic configuration.
Describe how the electrical conductivity of sodium compares to that of sulfur. Give a reason for your answer linked to their electronic structures.
Name one exception among non-metals that can conduct electricity and explain why it is an exception.
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) Diagram of a carbon atom: 2 electrons in the first shell, 4 in the second; shells shown as circles, electrons as dots or crosses. · must show Two shells, 2 electrons in inner shell, 4 electrons in outer shell, Electrons as dots or crosses
(b) Metal; X is sodium which has one electron in its outer shell and is in Group 1 (metals). · must show States metal, Explains outer shell (1 electron), Links to Group 1
(c) Sodium conducts electricity, but sulfur does not. This is because sodium has a delocalised electron that can move, while sulfur has no free electrons or mobile ions. · must show Compares sodium and sulfur, Sodium conducts, sulfur does not, Links to electronic structure (delocalised/free electron)
(d) Graphite (a form of carbon); it is an exception because it has free electrons between its layers. · must show Graphite, Reason: has free/moving electrons
Show mark scheme and worked solution
Marking points
A1 (a) · 1 mark · Draws two shells with the correct number of electrons (2, 4), electrons shown as dots or crosses.
B1 (a) · 1 mark · Diagram is clearly labelled or accurately shows electrons on shells.
A1 (b) · 1 mark · Correctly states X is a metal (sodium).
B1 (b) · 1 mark · Explanation uses electronic configuration (outer shell electron / Group 1).
A1 (c) · 1 mark · Describes sodium conducts, sulfur does not.
B1 (c) · 1 mark · Links conductivity to delocalised/free electrons in sodium and lack in sulfur.
A1 (d) · 1 mark · Names graphite (as exception) and gives correct explanation (free electrons).
Worked solution
a) The electronic configuration of atomic number 6 (carbon) is two electrons in the first shell, four in the second. The diagram should show two concentric circles: first with two dots/crosses, second with four.
First shell: 2 electrons, second shell: 4 electrons (dots/crosses arranged evenly).
b) X with configuration 2,8,1 is sodium. It is a metal because it has one electron in its outer shell, typical of Group 1 metals.
c) Sodium conducts electricity, while sulfur does not. This is because sodium has a single delocalised electron in its outer shell, free to move and carry charge, but sulfur’s electrons are held tightly and it has no mobile ions.
d) Graphite is a non-metal that conducts electricity. It has free electrons (delocalised) between its layers, allowing it to conduct.