How to draw polyatomic 3d vsepr shapes
How do I draw 3d polyatomic vsepr shapes? I'm talking about stuff like CH2O or N2H3F, those kind of things. We've never been thought in class how to draw such complex things, and yet it was in our test. I've managed to draw CH2O - it's a trigonal planar, but i'm stuck on N2H3F. I've managed to draw out a structure which was trigonal bipyramidal, but it violates the octect rule.
Plz show me a trick to how to draw these stuff
Also, how do I determine if the compound is polar covalent or not? I would usually subtract the electronegativity from each other, but having so many atoms, I would be in the negatives.
Thank you!
[url=http://imgur.com/Vrm8qji]Is this correct?[/url]
January 26, 2015
3 Comments • Newest first
Bruh, it's actually really simple. Like, probably the easiest thing that you can learn in chemistry
Here are some links about vsepr 3d drawings.
https://www.youtube.com/watch?v=Wv5tn-Y2XZQ
http://phet.colorado.edu/en/simulation/molecule-shapes-basics
http://www.smc.edu/projects/28/Chemistry_10_Experiments/Ch10_Molecular_Shapes.pdf
The structural formula doesn't give you a lot of information on what it looks like so you need to know by experience and drawing a few to see what it looks like. The basic structures are the ones where an atom is bonded to 4 substituents and a few others like the sulfur that can bond with more than 4.
N2H3F is pretty easy because H and F can only bond once so you know when you have your structure they will be sticking out in the exterior and the core will be the two nitrogens. So it will be like two trigonal pyramidal shapes connected to the other through the hydrogens. Nitrogen bonds 3 times usually with a lone pair (4 "substituents" in total) so it doesn't violate the octect rule. Its polar because it has the lone pair of electron on both nitrogens and if you think about it (imagine the F and H as large spheres) one nitrogen has to be on an angle to the other and you get a dipole from both e- pairs in the same direction making it polar.
Also polarity is a function of its shape (have you learned about vectors in math) not just the bonds. When a molecule is polar it means that in the large electron density surrounding the molecule, one side (polar) will have less e- on average and the other side more e-. For example CO2 is not polar despite C-O bonds being polar, the molecule is non polar because the shape is linear and both sides of the molecule (oxygen) have e- densities so there isn't a side with more than the other. If its a 3d molecule like N2H3F then you gotta look at in 3d.
Idr vseprs that well anymore but I'm pretty sure to check for polar covalent bonds, you can check to see if the molecule is symmetrical in all axes. If the electronegativities in all directions cancel out, then the molecule won't have any polarity.