Group 0 elements (the noble gases) including Helium, Neon and Argon, exist as single, unattached particles. They are stable atoms. They have fuller outer energy levels so they do not usually form molecules with other atoms.
They have low melting and boiling points as they are easily separated by overcoming the weak forces of attraction between the atoms.
|Monatomic (noble gas)||Low||Low||Non-conductor|
|Covalent molecular (N2, P4, S8)||Low||Low||Non-conductor|
|Covalent network||Very high||Very high||Non-conductor (except graphite)|
|Metallic lattice (all metals)||High||High||Conductor|