[tangent1.57]

Why are double-bonds electrophilic when, in fact, there are a lot of electrons in that area?  C=C should be electro-phobic!

[nj_bartel]

They generally behave as nucleophiles.

[orgoclear]

C=C bonds undergo ELECTROPHILIC ADDITION reactions because there is a pie-electron cloud surrounding the sigma bonded C-C. This makes the attack of an electrophile easier. Further as the C-atoms are sp² hybridised, so, their electronegativity increases compared to sp³. Hence they behave as nucleophiles

[ufalynn88]

if you draw the resonance structure of C=C, you get C+-C- (ie one C with a positive charge and the other negative)..obviously the atoms would rarely exist like this for any amounts of time...however this still shows the nucleophilic nature of the carbon....

[chalconix]

C=C bonds undergo ELECTROPHILIC ADDITION reactions because there is a pie-electron cloud surrounding the sigma bonded C-C. This makes the attack of an electrophile easier. Further as the C-atoms are sp² hybridised, so, their electronegativity increases compared to sp³. Hence they behave as nucleophiles

in fact there is an empty π* (LUMO) which is easily filled and the π-bond is breaking.

[luiee]

there is an empty pie* (LUMO),not n*  , easily filled and the pie-bond is breaking

[luiee]

MAYBE there is an empty pie* (LUMO),not n*  , easily filled and the pie-bond is breaking