Arrangement vs Shape

(Polar molecules, Non-polar molecules, etc.)

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katherinemurk 2B
Posts: 68
Joined: Wed Nov 15, 2017 3:02 am

Arrangement vs Shape

Postby katherinemurk 2B » Thu Nov 15, 2018 11:38 am

Can someone please clarify what the difference is when asked for arrangement vs when asked for molecular shape? I know it has something to do with the lone pairs but im not entirely sure

Sofia Ban
Posts: 80
Joined: Fri Sep 28, 2018 12:25 am

Re: Arrangement vs Shape

Postby Sofia Ban » Thu Nov 15, 2018 12:03 pm

I think that when asked for the arrangement, it's asking for all single, double, triple bonds as well as lone pair electrons (Lewis Structure). For molecular shape, it may want just the positioning of the atoms without showing what kinds of bonds are attached (almost like a simple 3D drawing) and the name of the shape (octahedral, linear, trigonal planar, etc.)

Manu Vohra 1L
Posts: 61
Joined: Wed Oct 03, 2018 12:15 am

Re: Arrangement vs Shape

Postby Manu Vohra 1L » Thu Nov 15, 2018 1:19 pm

The arrangement is dependent only on the number of regions of electron density whereas the molecular geometry has to take into account the number of bonded electrons vs. the number of lone pairs and how they interact among each other (lone pairs force bonded atoms closer together and therefore create a different shape and slightly lower bond angle than would be expected of typical molecules with the same arrangement and no lone pairs).

Schem_student
Posts: 29
Joined: Fri Sep 28, 2018 12:19 am

Re: Arrangement vs Shape

Postby Schem_student » Thu Nov 15, 2018 1:25 pm

Also you can learn molecular shape alot easier if for some lewis structures you start to draw them similar to their Molecular shape. This can be true for bent, trigonal planar, and seesaw.


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