I'm doing pastpapers and there's a question in which it has been asked whether a compound has permanent dipoles or induced dipoles. Compounds are: i) CH3CHO ii) CH3CH2OH ii) CH3OCH3 iv) (CH3)2CHCH3 I do realise that fourth one has induced dipoles since hydrocarbons always have induced dipoles but how to determine for other three? Please reply asap!
Every molecule has induced dipoles, since they only depend on whether the molecules has electrons within it (and they all do)!
Permanent dipoles form when two atoms in the molecule have a significant difference in electronegativity. Carbon and Hydrogen do not. Hydrogen and Oxygen do, so will form permanent dipole-dipoles (and also hydrogen bonds!)
Every molecule has induced dipoles, since they only depend on whether the molecules has electrons within it (and they all do)!
Permanent dipoles form when two atoms in the molecule have a significant difference in electronegativity. Carbon and Hydrogen do not. Hydrogen and Oxygen do, so will form permanent dipole-dipoles (and also hydrogen bonds!)
Also carbon and oxygen do so aldehydes and ketones have permanent dipoles and I am fairly certain.
Every molecule has induced dipoles, since they only depend on whether the molecules has electrons within it (and they all do)!
Permanent dipoles form when two atoms in the molecule have a significant difference in electronegativity. Carbon and Hydrogen do not. Hydrogen and Oxygen do, so will form permanent dipole-dipoles (and also hydrogen bonds!)
I'm doing pastpapers and there's a question in which it has been asked whether a compound has permanent dipoles or induced dipoles. Compounds are: i) CH3CHO ii) CH3CH2OH ii) CH3OCH3 iv) (CH3)2CHCH3 I do realise that fourth one has induced dipoles since hydrocarbons always have induced dipoles but how to determine for other three? Please reply asap!
It all mostly comes down to difference in electronegativity, as you know electronegativity increases going towards Fluorine so across the period and up the group, the higher the DIFFERENCE in electronegativity, the stronger the dipole, with the posibility of permanent dipole. If you're struggling, refer to the electronegativity values of each element and compare them; like someone mentioned before C and H are too similar in terms of electronegativity there so there's no permanent dipole, just induced but for something like H and F, there is a permanent dipole. Also, permanent dipoles usually result in polar molecules so usually alcohols, aldehydes, ketones, etc. (Correct me if I'm wrong, not sure about ketones here)
CF4 has polar bonds, but is a non-polar molecule and hence only forms idd.
OP: you may find this of use in answering your second question (ii).
That is not quite right. It doesn't only form Induced dipole - dipoles. It forms permanent dipole-dipoles, but since the molecule is symmetrical, they 'cancel eachother out' hence it does not have any effect on the molecules polarity. They do form though.
It forms permanent dipole-dipoles, but since the molecule is symmetrical, they 'cancel eachother out'
It seems you are saying that the pdd 'cancel each other out'. Are you suggesting that the d+ C is attracted to the d- F on another molecule and that cancels out the d- F to d- F repulsion equally?
since the molecule is symmetrical, they 'cancel eachother out' hence it does not have any effect on the molecules polarity.
I really don't like my students using the word it as it rarely is clear what they are referring to. My guess is that you are suggesting that the fact that the molecule is symmetrical does not have any effect on whether the molecule is polar or not. Curious as you mentioned 'cancel eachother out' based on the symmetry.
I really don't like my students using the word it as it rarely is clear what they are referring to. My guess is that you are suggesting that the fact that the molecule is symmetrical does not have any effect on whether the molecule is polar or not. Curious as you mentioned 'cancel eachother out' based on the symmetry.
They form but are instantly cancelled out. How can you know/show/test whether they are there?
It was referring to the fact that since the molecule is entirely symmetrical, the pdd's do not have an effect on the polarity of the molecule. They may be cancelled out, but that doesn't mean the pdd's don't form. There is a separation of electric charge, just the same separation all around the molecule, I think.