I want to know about the order of +and- ieffect?
Answers
Answer:
ALERT: I've taken a very fundamental approach to try and understand this in a very subtle way at a very basic level. So if you just want a increasing or decreasing order else if you're a beginner stay away.
Basically the inductive effect is just the slight push or pull of electron density arising due to electronegativity difference.
So next time if you want to check I effect just find out whether there exist electronegativity difference or not.
The next question likely to pop up is “then why in acetic acid the C-C bond has I effect when the bond is homonuclear?” OR “why do hydrocarbons show inductive effect?”
If this question really popped up in your mind then first congratulations you've got an inquisitive mind.
As to the answer the point that you've got wrong is that you've assumed that all the homonuclear atoms have the same electronegativity which is not the case. Both the atoms as in case of acetic acid are further bonded to different atoms altogether so electron density around them is also different. Obviously carboxylic acid group carbon has a lower electron density, hence there exist an -I effect here, in favour of carboxylic acid group.
Infact even a C-H bond as in hydrocarbons has 0.2 (Pauling scale) electronegativity difference which causes the I effect in them, although due to the small value of En. difference the effect usually is negligible after 3/4 carbons.
I've more baffling examples here but I'll stop right here. If anybody is interested further go on comment or upvote.