Intuition with shape
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Intuition with shape
How do you guys intuitively guess what a shape will be without having to draw out each of the bonds. is there a tip or trick to know if a molecule will be in a certain family of shapes so that i could theortetically eliminate some multiple choice questions?
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Re: Intuition with shape
I think it just comes with practice. However, I totally recommend NOT going by intuition, especially on a test. Draw out the molecule, be thorough. This saved me a question on the last midterm, because your answer can be different from formal charges.
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Re: Intuition with shape
Hi! There's no "intuitive" way to determine shape. The safe way is to always first draw the Lewis structure - include all lone pairs and single/double/triple bonds. Then, counting the number of bonded pairs and lone pairs, you can determine the electron domain geometry and the molecular geometry. I'd recommend first memorizing all the shapes and then doing lots of practice with Lewis structures & naming their molecular geometries.
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Re: Intuition with shape
It's always safer to draw the molecule and determine its shape from there. Practice definitely helps build your intuition if you drew the molecule right, but it won't let you predict the shape of the molecule without drawing it.
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Re: Intuition with shape
As others have said, always draw out the Lewis structures! This is the best way to determine shape, as you can easily see the number of bonds and lone pairs on the central atom. Intuition comes with practice - even when drawing out Lewis structures, pay attention to patterns (think about it in the form AXE, where X refers to the number of atoms bound to the central atom and E refers to the number of lone pairs on the central atom).
Re: Intuition with shape
Hi!
As everyone else has already said, I would definitely not recommend going off of intuition. I always like to draw out the lewis structure because that is the only way you can concretely know how many lone pairs the central atom has, which is extremely important to determining shape. Drawing lewis structures is not extremely time consuming, so I would definitely recommend just drawing it out.
As everyone else has already said, I would definitely not recommend going off of intuition. I always like to draw out the lewis structure because that is the only way you can concretely know how many lone pairs the central atom has, which is extremely important to determining shape. Drawing lewis structures is not extremely time consuming, so I would definitely recommend just drawing it out.
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Re: Intuition with shape
There isn't really intuition to it. You have to know how many lone pairs and bonds an atom has, so it can't be intuited. The people who seem to be able to do it intuitively are just able to calculate the number of lone pairs and bonds an atom has mentally, so they don't need to draw it out. However, if you are not one of those people, don't worry! Most people aren't. Just take your time and draw out the Lewis structures. This is also helpful in double checking formal charges to make sure that you've picked the most likely shape.
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Re: Intuition with shape
Drawing out the lewis structure is the best way to determine the geometric shape of the molecule. When doing practice problems, there were times where I thought it was a specific shape before drawing the structure, but turns out there were lone pairs on the central atom that I did not account for.
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Re: Intuition with shape
Yup, not really an intuition thing. There are probably a few molecules that you can memorize the shape of, like H2O or NH3, but other than that you need to be able to see the actual distribution of electrons. For example, ICl3 might look like it would be trigonal planar because there are 3 atoms bonded to the central atom, but without drawing the lewis structure you would never know that there are 2 lone pairs as well.
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Re: Intuition with shape
From my experience, I haven't found that there is really any type of intuition when it comes to molecular formulas and their shapes. However, as you get used to working with certain central atoms, I feel like there may be a correlation between the number of "electrons" needed to make the resonance number zero and the number of atoms surrounding the central atom. Practice is probably the best option though!
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Re: Intuition with shape
When determining the shape of a molecule, I find that there really isn't an "intuitive" way to go about it. Rather, what has worked for me is getting more familiar with molecular geometry and quicker with drawing Lewis structures so I can determine the shape from there.
This video was especially helpful for me! https://www.youtube.com/watch?v=_Cw0_cJzkSI
This video was especially helpful for me! https://www.youtube.com/watch?v=_Cw0_cJzkSI
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