exam question that ask you to compare bonding and structures really throw me, has anyone got any advice how to tackle these questions as they are often worth a large number of marks. Any good places to revise from? An example of a question was describe the structure and bonding in aluminium, strontium sulphide, SrS, and carbon dioxide. It was worth 10 marks.
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bonding and structure of molecules watch
- Thread Starter
- 11-06-2005 17:50
- 11-06-2005 18:25
just break it down into the four questions.. eg.
bonding in aluminium:
metallic, regularly arranged metal atoms with overlapping outer orbitals leading to delocalised electrons, held together by the attraction between positive neuclei and electrons.
carbon dioxide, simple covelant, carbon double covelantly bonded to two oxygen atoms. intermolecular bonds are Van der Waals bonds between carbon dioxide molecules.. etc.
that alone should be 5 marks (there were 3 distinct points in aluminium and 2 in carbon dioxide), the other two I don't know about. Just remember the keywords and make sure you understand the difference between the different types, eg. carbon dioxide is just little CO2s floating round, but NaCl, for example, is NOT little NaCl molecules floating round, these are arranges in a lattice which all relies on ionic bonds. So in solid CO2 you have covelant bonds between atoms to form carbon dioxide molecules, and between these molecules you have weaker bonds holding them together and stopping them from melting (or more accurately, subliming).
- 11-06-2005 18:31
Well we went through this one in class and i've written down some notes by the side of my answer, i got about 6marks on mine.
You have to talk about aluminium being metallically bonded and describe that (maybe alittle diagram of +ve ions with -ve electrons flowing round)
And then describe how Strontium sulphide is a large molecule which is covalently bonded in a large network, and how hte bonds here are more easily broken,
then with carbon dioxide how it is a simple molecule that is covalently bonded, but compared to strontium sulphide the bonds are much stronger.
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- Community Assistant
- Study Helper
- 12-06-2005 10:09
strontium sulphide is ionic not molecular there is no covalent bonding
strontium ions Sr2+ and sulphide ions S2- in a giant ionic lattice