[Zishi]

Here's the question:


I understand that SiCl₄ has got an empty 3d orbital and BCl₃ has an empty 2p orbital to accommodate lone pair from oxygen in water molecule, whereas carbon has no such things. But my problem is that the examiner report says:
"Many candidates knew the “Si has d orbitals” justification, but only a minority applied it intelligently. Carbon - and boron, as it happens - both have 3d orbitals, of course, but they are too high in energy to be used in bonding. Being in Period 2, there is no way that boron could do this, since the 3d orbital is far too high in energy."

Is it really that obvious that elements in period 2 have got 3 shells? Since last two years I have been taught that the period number corresponds to the number of shells - so why now does a single examiner report says that carbon and boron have also got 3d orbitals? Is it really true?

[EierVonSatan]

Every atom has every type of orbital but only a few are filled/used.

I'm sure you've seen the different spectral series of hydrogen - where the energy levels are represented by lines that get closer together? These are electrons being promoted up to much higher energy levels/orbitals than H would normally use in typical chemistry - but they are there

[Zishi]

(Original post by EierVonSatan)
Every atom has every type of orbital but only a few are filled/used.

I'm sure you've seen the different spectral series of hydrogen - where the energy levels are represented by lines that get closer together? These are electrons being promoted up to much higher energy levels/orbitals than H would normally use in typical chemistry - but they are there

Yeah, I learned discrete energy levels in Physics. Thanks.

[LegendX]

(Original post by Zishi)
Here's the question:


I understand that SiCl₄ has got an empty 3d orbital and BCl₃ has an empty 2p orbital to accommodate lone pair from oxygen in water molecule, whereas carbon has no such things. But my problem is that the examiner report says:
"Many candidates knew the “Si has d orbitals” justification, but only a minority applied it intelligently. Carbon - and boron, as it happens - both have 3d orbitals, of course, but they are too high in energy to be used in bonding. Being in Period 2, there is no way that boron could do this, since the 3d orbital is far too high in energy."

Is it really that obvious that elements in period 2 have got 3 shells? Since last two years I have been taught that the period number corresponds to the number of shells - so why now does a single examiner report says that carbon and boron have also got 3d orbitals? Is it really true?

what examboard / year was this question on?

[Zishi]

(Original post by LegendX)
what examboard / year was this question on?

CIE, June 2010.