Optical Isomerism

Optical Isomerism. A-Level Chemistry teaching/revision resource

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  Science & Technology

[Arjun Verma]

Just me or is this video trippy?! I learnt it perfectly but its so colourful and all with music in the background, thats the hypnotherapy way of teaching kids lol

[Jayanth Lal Gudivada]

FIRST CLASS

[SciCommStudios]

One of our most frequent complaints from UK teachers is that YouTube teaching resources often have inappropriate language for the level they are supposedly pitched at and thus confuse students.

Whatever the correct term (and "stereogenic centre" is as good as any), we used that most acceptable to UK A-Level students, teachers and examiners.

The UK specifications are due to change. If "stereogenic centre" is adopted into the new specifications then we may revisit this resource. Until then...

[nemeczek67]

The phrase "asymmetric carbon atom" means that the space around this carbon atom is chiral. The atom itself is not. Just Google "stereoisomerism and local chirality" - one of the top hits will be a paper by Kurt Mislow and Jay Siegel. Additionally, in one of the footnotes (26) they deal with chirality of atoms.

[nemeczek67]

The "chiral atom" phrase is indeed prevalent. But the problem is that for an object to be chiral, it cannot be identical with its mirror image. Any atom is the same as its mirror image. The molecule C*ABCD is chiral, but it does not follow that its components (atoms, substituents) are. To avoid this ambiguity, atoms that you call chiral are referred to as stereogenic centers. Check, for example, this

DOI 10.1524/zkri.2009.1230 (just Google this DOI and you will get access to the full paper).

[SciCommStudios]

For reference, the relevant sections in the three main specifications are: "know that an asymmetric carbon atom is chiral" AQA GCE Chemistry (2012) "demonstrate an understanding of the existence of optical isomerism resulting from chiral centre(s) in a molecule with asymmetric carbon atom(s)" Edexcel GCE Chemistry (2012) "describe optical isomers as non-superimposable mirror images about an organic chiral centre: four different groups attached to a carbon atom;" OCR GCE Chemistry (2012)

[SciCommStudios]

These resources were designed for AS/A2 chemists and biologists. Scripts were proofread by chief examiners of both disciplines and none took exception. It is a phrase so commonly used that it would never be marked incorrect in an exam.

It could also be argued that "chiral carbon atom" is as colloquial as the alternative - "asymmetric carbon atom" - for the same reason. However, both phrases are quicker/easier to write and say than, "a carbon atom to which four different groups are attached"!

[Itachi Uchiha]

AWESOME !!!

[nemeczek67]

"a chiral carbon [atom]" is a colloquialism - atoms are never chiral.

[Qydra Fraz]

great video!