If double bonds are stronger than single bonds, why are alkenes more reactive than alkanes? thx?

Question

If double bonds are stronger than single bonds, why are alkenes more reactive than alkanes? thx?

Answer 1

Double (and triple) bonds consist of 1 sigma bond and 1 or 2 pi bonds. Although the pi bond adds strength to the sigma bond, it is the weaker of the two bonds, and is more reactive.

Most reactions in alkenes (double bonds) and alkynes (triple bonds) do not sever the sigma part of the bond but merely add groups to the two atoms in the bond.

For example, Iodine (I2) adds across double bonds.

WXC=CYZ + I2 >>>>> WXIC-CYZI

Answer 2

Double bonds are most easily breakable during addition reactions .In carbon compounds double bonds are unstable than single bonds .

Answer 3

A double bond is stronger than a single bond.  However, it is not twice as strong as a single bond.  In other words, two single bonds are stronger than one double bond.

You can use molecular orbital theory to explain why alkenes are more reactive than alkanes.  A single bond is one sigma bond; a double bond is a sigma bond and a pi bond.  A sigma bond is stronger than a pi bond and lies along a line betweeen the two nuclei involved in the bond.  A pi bond lies above and below the plane of the nuclei involved in the bond.  Therefore, reactants can more easily access the electrons in the pi bond.  So, its the pi electrons reacting from a double bond, which are less tightly bound than sigma electrons.

Answer 4

The electrons in the bonds are more exposed and something with a strong positive charge might pull them away.  It is not like it would pull the electrons of both bonds.