What is the average mass of 1 atom of chlorine?

the mol mass of chlorine atom is 35,453 g/mol.

there are 6,022 141 79 × 1023 atoms in one mol.

So one atom of chlorine would weigh around 5.83 x10-23 grams.

Chlorine,the molecule, would be twice as heavy since the gas consists out of two chlorine atoms.