Chlorine is a gas at room temperature. Chlorine is a highly reactive substance, it has the highest electron affinity, and thus is rarely found in molecular form in the atmosphere. Its most common compound on Earth is NaCl, or common table salt.
Neon is one of the noble gasses. Neon's outer shell of electrons has the full complement of eight, and thus neon will not form ionic bonds with other elements.(There is some evidence for a compound formed with flourine, but this is not generally accepted.) Neon is thought to be inert, unable to form neutral compounds. Some ions of neon have been observed to form compounds such as ` ``("NeAr")^"*" ` .
So the answer is, nothing. Despite chlorine's strong reactivity, neon will not form a compound with chlorine since neon is inert.
There is a van der Waals compound with neon and chlorine, but I don't believe that is what you are asking about.
Nothing will happen when chlorine is mixed with neon because there is no gain or lost in any electrons in the mixture.
This relates to the Octet rule. Neon is a noble gas and has 8 valence electrons already. Chlorine on the other hand is a halogen and has 7 valence electrons. Therefore chlorine is in search for that extra valence electron to reach it's full 8 valence electrons. Since neon has 8 valence electrons and has no need to gain or lose any electrons, nothing will happen when they mix.
A key theory in this situation is the Octet Rule. All atoms wish to become like the noble gases and have a full shell of valence electrons. With eight valence electrons, atoms are able to mimic the stability that noble gases possess.
Chlorine is a halogen and has seven valence electrons. This makes chlorine reactive in search for that additional valence electron.
However, neon is a noble gas and already has eight valence electrons. It is "content" and does not wish to gain or lose any more valence electrons.
Therefore, nothing will occur.
Nothing will happen
Although chlorine is a halogen (has 7 valence electrons) and is highly reactive in its pure state, neon is a noble gas which has a full outermost electron shell, which makes it completely unreactive under most conditions.
Therefore, nothing will happen when they are mixed.
Nothing will happen because Neon is a noble gas and is very unlikely to react as it has its outer level filled.