AQA A Level Chemistry Bonding

Would anyone be able to explain why CH3Cl shape is tetrahedral and not trigonal pyramidal even though there are 3 hydrogens bonded to the carbon.And why it has a permanent dipole ?
I think it doesn't have a permanent dipole as it's not symmetrical and because of the negative charge of the chlorine?

Reply 1

z.sh123

2

its tetrahedral as it has four bonding pairs the Carbon is bonded to 3H atoms and one Cl atom. if it had three bonding pairs and one lone pair it would be triagonal pyramidal but its has 4 bonding pairs and no lone pairs. not too sure about the dipole part. hope that helps :smile:

Original post by anon25x

Would anyone be able to explain why CH3Cl shape is tetrahedral and not trigonal pyramidal even though there are 3 hydrogens bonded to the carbon.And why it has a permanent dipole ?
I think it doesn't have a permanent dipole as it's not symmetrical and because of the negative charge of the chlorine?

Reply 2

TypicalNerd

18

Original post by anon25x

Would anyone be able to explain why CH3Cl shape is tetrahedral and not trigonal pyramidal even though there are 3 hydrogens bonded to the carbon.And why it has a permanent dipole ?
I think it doesn't have a permanent dipole as it's not symmetrical and because of the negative charge of the chlorine?

It is tetrahedral, since there are four bonding pairs - 3 come from C-H bonds and the fourth from the C-Cl bond. There are no lone pairs.

The dipole forms because Cl is more electronegative than carbon, so it draws the electrons in the bond closer to itself. This makes the Cl weakly negative and the C weakly positive. Dipoles only cancel when you have multiple that face opposite directions, but since there is only one dipole, this does not occur and CH3Cl is polar.