Polarity and size

[GRAD]

Which has a bigger dipole and how does it relate to polarity?
CH2Cl2 or CH2Br2???
I know you increase polarity as you move down the column, but i think the answer for this one was Ch2Cl2....????

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[Dr. juju]

Which has a bigger dipole and how does it relate to polarity?
CH2Cl2 or CH2Br2???
I know you increase polarity as you move down the column, but i think the answer for this one was Ch2Cl2....????

yes, it's CH2Cl2 because Cl is more electronegative than Br. This is only true in the case which they are in Cis position. Trans give no polar compound.

 

[GRAD]

but i keep reading that polarity increases as you move down from CL--->Br, etc. Is tis still true?? THanks!!

 

[Dr. juju]

but i keep reading that polarity increases as you move down from CL--->Br, etc. Is tis still true?? THanks!!

you're looking at a molecule, not an element. yes polarity of elements increases as you go down a group. but within a molecule, you have to consider electronegativity (ie, polar bond vs. non polar bond). since Cl is more electronegative, CH2Cl2 is more polar. since it's a molecule, you also have to make sure polarity does not cancel out (which in this case for the trans isomer, it does cancel out).
hope this helps 🙂

 

[GRAD]

but so its still that HBr is more polar than HCL in general? Sorry, i think ive gone dumb =)

 

[Dr. juju]

but so its still that HBr is more polar than HCL in general? Sorry, i think ive gone dumb =)

nope😛 polarity of a bond is determined by electronegativity. since they are both bound to the same atom (H in this case) the higher the difference in electronegativity the more polar the bond is. so HCl> HBr in terms of polarity.

lets say now, you're comparing I- and Br-. in this case I- will be more polar.

makes sense now? let me know...

 

[allstardentist]

i believe HCl is more polar than HBr.

 

[GRAD]

so polarity increases for COMPOUNDS as you get more electronegative, and for elements as you move down. k thanks JuJu

 

[Dr. juju]

so polarity increases for COMPOUNDS as you get more electronegative, and for elements as you move down. k thanks JuJu

you're welcome my friend 🙂

 

[allstardentist]

but u have to be careful of dipole moments cancelling out. so for example, CCl4 is less polar(in fact non polar) than CHCl3