When the atom has 8 valence electrons.
A chlorine atom needs one additional electron in order to become stable.
isotope
Nucleous
4
It can do either, depending on it's state previous to losing neutrons. Generally if an atom is shedding neutrons it is doing so to become more stable.
to become stable, it will gain an electron from a metallic atom otherwise it will mutually share electron(s) with another non - metallic atom, or even with itself
The only way a carbon atom becomes stable is if they gain or lose electrons. Typically carbon will bond with other elements to do this.
It becomes most stable when its nucleus is filled, not when it is filling it.
2
To become stable. When the outermost energy field is filled to maximum electrons, the atom is stable.
the oxidation number
Yes, Chlorine atom is stable