Assign E or Z to the following molecule:

Priority is determined by the atomic number of the atom directly attached to the double bond.

• For the left carbon atom:

  • Group 1: Cl (Atomic number = 17)
  • Group 2: H (Atomic number = 1)
  • Priority: Cl > H. So, Cl is the higher priority group.

• For the right carbon atom:

  • Group 1: Br (Atomic number = 35)
  • Group 2: Cl (Atomic number = 17)
  • Priority: Br > Cl. So, Br is the higher priority group.

• The higher priority group on the left carbon (Cl) is positioned upwards.
• The higher priority group on the right carbon (Br) is also positioned upwards.

Since both higher priority groups are on the same side of the double bond, the configuration is Z (from the German word "zusammen," meaning "together").

The E/Z configuration of the molecule is $\text{Z}$.