Group 1 metals always +1, Group 2 always +2 .....Sum of oxidation numbers in a coumpound = 0. etc (look up the rest of the rules) On this basis oxidation state Na = +1. The answer for this question is: In Na2O oxidation state of Na is +1.. Access detailed answers to various other Science and Maths questions at BYJU'S. The oxidation number of each atom can be calculated by subtracting the sum of lone pairs and electrons it gains from bonds from the number of valence electrons. So you then work backwards, deciding if it's $\ce{Na+}$ then you have +2 from the sodium, and oxygen must have an average oxidation number of -1 per oxygen atom. There are two Na here so total +2. O: -2 -2 -----> -2. Na: +1 ----> +1. Oxidation-reduction reactions, or redox reactions, are characterized by changes in the oxidation state of elements after the reaction. Oxygen can take multiple oxidation states. Different ways of displaying oxidation numbers of ethanol and acetic acid. There is no oxidation number for compounds. The alkali metal oxides M 2 O (M = Li, Na, K, Rb) crystallise in the antifluorite structure. Bonds between atoms of the same element (homonuclear bonds) are always divided equally. - Join Now! Figure 1. The oxidation number for the calcium in CaSO4 is 2+, the oxidation number for oxygen is 2-, and the oxidation number for sulfur is 6+. This particular compound is sodium peroxide.. You're right that usually oxygen has a charge of -2, but in this case, there's no way that each $\ce{Na}$ can have an oxidation state of +2.. There are a number of rules for oxidation states; e.g. Hence O = -2, in order for total oxidation number of the compound to be 0. What I was taught to do was write out the oxidation numbers under the equation. H: +1 ----> +1 Sodium oxide is a chemical compound with the formula Na 2 O.It is used in ceramics and glasses.The compound is the base anhydride of sodium hydroxide; when water is added to sodium oxide, NaOH is produced.. Na 2 O + H 2 O → 2 NaOH. So: Na2O + H2O ---> 2NaOH.