When writing overall ionic equations, when you have a single atom or diatomic by it self, ex: H2, do you...?

Question

write it as 3Cl2 +xxx -> xxx + yyy
or as 6Cl +xxx -> xxx + yyy
because i know you would write it as 6Cl if it had been broken down into ions from a molecule but as this im not sure

Answer 1

Anything covalent like H2O or Cl2 or H2 or O2 or CO2 must be left as it is.

Only if they have gained electrons to form ions can they be broken up.

Cl2 + 2e- ----> 2Cl-.