Disulfate ion (S2O72-) Lewis Structure, Oxidation Number

In the lewis structure of disulfate (S2O72-) ion, sulfur atoms are located as center atoms and oxygen atoms are located around sulfur atoms. There are two double bonds around a sulfur atom in the lewis structure. Oxidation number of sulfur is six in S2O72- ion.

Disulfate ion (S2O72-) Lewis Structure

In the lewis structure of disulfate ion, each sulfur atom has attached to four oxygen atoms. One oxygen atom has attached to the two sulfur atoms through single bonds.

Disulfate ion - S2O72- Lewis Structure

Oxidation number of S2O72-

There are six bonds around sulfur atom. All these bonds are made with oxygen atom. Because oxygen's electronegativity is higher than oxygen, sulfur atom should get positive oxidation number. Therefore sulfur's oxidation number should be +6.

oxidation number of S2O7 2-

Algebra method to calculate oxidation number of S2O72-

Above, we determined the oxidation number through the structure of the S2O72- ion.

But, we have an another method to calculate the oxidation number of sulfur atom in S2O72- ion. We know, most times oxygen's common oxidation number is -2. Then, we take sulfur's oxidation number as x (unknown value).

  • Summation of oxidation numbers of all elements = overall charge of ion or molecule
  • Summation of oxidation numbers of oxygen atoms + Summation of oxidation numbers of sulfur atoms = -2
  • (-2) * 7 + x*2 = -2
  • x = +6


Lewis Structures of Molecules