Atom Connectivities

[Sameer Chowdhury 3C]

For week 7/8 sapling problems, number 17 asks about resonance structures. It mentions in the solutions that resonance structures must all have the same atom connectivities. Could anyone explain to me what that is?

[Vivian Hoang 1H]

I think connectivity refers to the way they are attached, or in other words, the pattern of chemical bonds between the atoms.

[IreneGi2I]

The atom connectivity means the specific pattern of chemical bonds between atoms in a molecule!

[Pranav Kadiyala 1A]

To elaborate, resonance structures solely mean the delocalization of electrons, meaning the only thing that can change are the locations of electrons (like the movement of a double bond). The atoms must remain in the same place, as said above, and connected to the same atoms in the same position for it to be resonance.

[Rose_Malki_3G]

It means that the atoms are not being moved but rather it is the actual electrons that are delocalized/move to create different resonance structures.

[AnnaNovoselov1G]

Connectivity refers to how atoms are connected/arranged.
If 2 molecules have the same molecular formula, but different connectivity, they would be called constitutional isomers. Isomers are molecules that have the same formula but different shapes.

Here's an example to illustrate the concept:

2-methylpentene and 3-methylpentene have the same molecular formula, but in 2-methylpentene, the methyl group is attached to the second carbon, but in 3-methylpentene, it's attached to the third carbon.