Sapling #20

[Gabby Magat 3F]

Could someone explain the last part of #20 on the Sapling homework for Weeks 7 and 8? The solution explains that [ AsO4 ]3- is nonpolar due to the symmetry (since it's a tetrahedral shape). If all three of the negatively-charged oxygens are on the "same end" how do they cancel? Wouldn't the dipole vectors point at an angle?

[Nick Pascua 2L]

Hello,

I believe the charges do not matter when considering dipole vectors. All oxygen atoms will have the same electronegativity value and since it's a tetrahedral, yes they will all cancel out.

[Sera Aintablian 2E]

Since all three atoms are electronegatively charged and are the same elements, the dipole moments cancel out.

[Natalie 3k]

Hi, I think that because it's the same element with the same electronegativity that's on all the sides, it cancels out. I was kind of confused on whether or not the charges would affect the polarity too but I don't think it does because then it would seem to be polar.

[Pranav Daggubati 3C]

The fact that it is an ion doesn't change its polarity. Another thing is resonance in the structure causing even distributions of all forms of [AsO4]3-.

[Gabby Magat 3F]

Hello,

I believe the charges do not matter when considering dipole vectors. All oxygen atoms will have the same electronegativity value and since it's a tetrahedral, yes they will all cancel out.

Ohh thank you, this makes more sense now!

[Gabby Magat 3F]

The fact that it is an ion doesn't change its polarity. Another thing is resonance in the structure causing even distributions of all forms of [AsO4]3-.

Thanks for adding this!

[Gabby Magat 3F]

Hi, I think that because it's the same element with the same electronegativity that's on all the sides, it cancels out. I was kind of confused on whether or not the charges would affect the polarity too but I don't think it does because then it would seem to be polar.

Yeah, everyone's explanations help this make more sense--I thought the polar bonds meant the molecule had to be polar, but I guess it comes down to the electronegativity difference/molecular shape.