The salts of #"sulfuric acid"# are called #"sulfates"#....in which sulfur assumes the #S(VI+)# oxidation state...
On the other hand, the salts of #"sulfurous acid"#, #H_2SO_3#, are called #"sulfites"#,....in which sulfur assumes the #S(IV+)# oxidations state...The counterion is #SO_3^(2-)#...
And the salts of #"hydrogen sulfide"# are called #"sulfides"#, the analogue of oxides, and here we gots #S(-II)#....
Sometimes we represent #H_2SO_3# as #H_2O*SO_2#, i.e. water saturated with #SO_2#. The smell of sulfurous acid is sulfurous, but many people, including me, find the smell pleasant, and clean, and antiseptic.
So finally, #CuSO_4-="copper sulfate"#, and #CuSO_3-="copper sulfite"#, and #CuS-="copper sulfide"#. And in each salt we gots #Cu^(2+)#, #"cupric ion"#.
