Carbonate is CO32- ion and the oxidation numbers are +4 for carbon and -2 for each oxygen.
+4 for carbon
Tl2CO3
I believe K2CO3.
Carbon has an oxidation number of +4 in both carbonate and bicarbonate. Oxygen as usual has an oxidation number of -2, and hydrogen has an oxidation number of +1. Therefore, the ion CO3-2 has six negative charges from oxygen partly balanced by four positive changes from carbon for a net of -2, and HCO3-1 has six negative charges from oxygen partly balanced by one positive from hydrogen and needs for plus four from carbon for an overall value of -1.
+2 for Mg, +4 for C, -2 for each O in MgCO3
Magnesium and carbonate are divalent.
Barium Carbonate is BaCO3 and the oxidation numbers are +2 for barium, +4 for carbon and -2 for each oxygen.
+4 for carbon
Na2C03 Oxidation number of Na = + 1 Oxidation number of O=-2, Oxidation number of C=2x1+x+3(-2)=0 so x=4
Tl2CO3
I believe K2CO3.
Carbon has an oxidation number of +4 in both carbonate and bicarbonate. Oxygen as usual has an oxidation number of -2, and hydrogen has an oxidation number of +1. Therefore, the ion CO3-2 has six negative charges from oxygen partly balanced by four positive changes from carbon for a net of -2, and HCO3-1 has six negative charges from oxygen partly balanced by one positive from hydrogen and needs for plus four from carbon for an overall value of -1.
In the carbonate CO32- the sum of the oxidation numbers is the ionic charge (true for all poyatomic ions) O is assigned -2 so C has +4. (maths 4 +(-6) = -2)
+2 for Mg, +4 for C, -2 for each O in MgCO3
We can find this in bleaching powder. Chlorine shows +1 oxidation number.
+2 for Be, +4 for C, -2 for each O in BeCO3
+3 for each Al; +4 for each C; -2 for each O