Point group examples from previous GATE exam - Allenes, Ethane etc

[@deepthikorabandi]

Point group of allene is D2d

[@Jitendra-hd8ew]

Point group of allene is D2d & it has S4 symmetry element.

[@nenavathparvathalu5012]

Nice Explanation. Thank you ma'am.

[@siya1237]

C2 is the principal axis in Allene point group

[@RamaDevi-cy2vx]

Mam how u directly said it is 120or180degrees rotation

[@amirhosseintalebi6770]

Fantastic and thanks a lot. Just "Like and Share" does not let me to see some notes.

[@lonelalydmitri9489]

Point group of allene is S4, F A cotton would like to know your location

[@siya1237]

Allene me C2 axis hoti h

[@sagarsrivastava3462]

Point group of allene is D2d or S4 . Mam please explain

[@pchemistry924]

Mam apki vedio and aapkae previous year question c net clear ho jayega mam plz. Reply me

[@pchemistry924]

Mam Maine June net crack karna h

[@asokk.mukherjee3422]

It is D2d and NOT S4. The flow chart in standard text book (Cotton/Cartar) should be strictly followed, otherwise wrong point groups will be found. First see that there is a C2 axis ( the C-C-C line) , then there are two C2 axes perpendicular to the C-C-C line. Next see that each plane containing a terminal C atom and the two H atoms attached to it is a plane of symmetry cutting the remaining part of the molecule into two equal halves. With the two terminal C atoms there are two such planes intersecting at the C-C-C line(the principal C2 axis). These are dihedral planes. so the point group is D2d. The S4 axis is a consequence of Sigma-d planes and C2 axes existing together.

[@rohanmanchanda7376]

Thank you mam

[@sivaraj-oq8sk]

Thank you very much for your beautiful explanation. Request you to explain on how to find out no of symmetry elements. Also request you to explain about diborane symmetry elements, point group

[@PriyankaJainchemistry]

I have already uploaded videos on this, plz watch playlist of group theory