Hey there. So this mcq is a bit weird. If I see values from the data booklet the ans is A. But the ms says the correct ans is C . I'm not sure if this is a mistake by CIE or if there is a logical explanation for this. Please any help would be appreciated
CIE's mistake? Help with mcq watch
- Thread Starter
- 07-06-2016 13:52
- 07-06-2016 14:31
Hey good question!
Sorry I'm also an A level student plus I'm not even doing the CIE exam board so I've got no idea if my answer will be satisfactory
The way I see it, this question is probably looking to test your understanding of factors which affect atomic radius, which is essentially that if all species have the same number of electrons (or at least in the same period), then increasing number of protons in the nuclei will lead to decreasing atomic radii (similar shielding, same number of electrons, more protons, greater effective nuclear charge experienced etc)
I think the problem with using data book values to confirm this question is that the way the values are calculated for Ne compared with Na+ and F- are different, since neon doesn't form bonds (noble gas). The way chemguide puts it is like it's 'unsquashed' radii - suggesting that you'd likely find a higher value for neon than what you'd expect from the trend alone.
To be honest chemistry is riddled with exceptions to the rule, and I don't think the exam board is looking for people to memorise the exceptions (unless specifically told to), but instead apply knowledge of chemistry to generalise, which is also known as deductive reasoning.Last edited by Spectral; 07-06-2016 at 14:32.