C2 – Structure and Bonding Test A Reflection

Corrections from Section B

Question 9. (c) State the type of structure and bonding shown in the diagram
My Answer: Covalent
Correct Answer: Simple

I was wrong because I did not mention that it is a ‘simple’. We had to mention the type of structure and bonding, I only mentioned the type of bonding.

Question 10. (c) Lead forms two ions +2 and +4. Write the formula for the lead chloride that does not include the lead ion with the same charge as the calcium ion.
My Answer: PbCa2
Correct Answer: PbCl4

I made a very silly mistake and for some reason, I used calcium instead of chlorine. What I should have done is used the method for lead and chlorine (with the charge of +4) which would have given me Pb2Cl4 which can be simplified to PbCl2.

Question 12. (b) In another reaction lithium was burnt in chlorine, the only product formed is lithium chloride. With reference to structure and bonding, explain how lithium and chlorine combine to form lithium chloride. In your answer, you should refer to the type of bonding formed and explain any changes in the electron configuration to lithium and chlorine atoms.
My Answer: Lithium is a metal and chlorine is a non-metal and this it is ionic bonding. Lithium loses an electron to form a cation as chlorine gains an electron to form an anion. This is because non-metals have a strong pull and tend to gain electrons and metals have a weak pull and tend to lose electrons. The lithium and chlorine then have a full valence shell as well as a positive charge for lithium and negative charge for chlorine.
Correct Answer: I had to add that there is “an opposite attraction between the electrons and the nuclei”.

I now understand that I simply had to mention this and I did not think to do so in the test. I knew this but I did not say it.

Question 12. (c) Suggest whether lithium oxide or lithium chloride would have the highest melting point. Explain your choice.
My Answer: Lithium oxide because there would be two lithium atoms. To join them, there would be two ionic bonds and only one for lithium chloride and thus, the melting point of lithium oxide would be higher.
Correct Answer: Lithium oxide (LiO2) has more bonds that two lithium atoms (Li2) and thus to break the bond, it would require a higher amount of energy to break the bonds and therefore, a higher melting point.

I was wrong because I did not use correct terminology and did not explain properly.

Question 13. (c) State the type of bonding and explain how this occurs. You should refer to the diagram in your answer.
My Answer: This is ionic bonding because ionic bonding is the electrostatic force of attraction between metal cations and non-metal anions. So, in the diagram, there are positively charged ions (cations) and negatively charged ions (anions). Thus the opposite charges attract and therefore and therefore we can tell that this is an ionic bond.
Correct Answer: I had to mention that “It is metallic bonding.”

It is not ionic and instead, it is metallic bonding because there is a sea of delocalised electrons.