Question

What are geometrical isomers?

Answer 1

These are isomers with identical connectivity, but different geometry, i.e. different spatial arrangement,

Explanation:

Consider `2-"butene"`; the pendant methyl groups can be on the same side of the olefinic bond to give the `"cis"` isomer, or on opposite sides of the olefin to give the `"trans"` isomer.

The key word is `"connectivity"`. In both isomers of `"2-butene"` `C_1` connects to `C_2` connects to `C_3` connects to `C_4`. Nevertheless, for `"2-butene"` we can draw geometric isomers that preserve this connectivity, but nevertheless have distinct geometries given the disposition across the olefinic bond.