Why is sulfur 2+ and iron 0 in Fe3S4?

Question

The compound Fe3S4 is magnetic. It is found in bacteria, which may use this magnetic property to help them be oriented in earth's magnetic field. If sulfur charge is 2+, the Fe charge is not an integer. How can you explain this?

(Hint: think of this mineral as a mixture of two different iron/sulfur compounds)

Please help explain this. Thanks!

Answer 1

Fe3S4 is a mixture of ferrous and ferric sulfide.  

Answer 2

Fe "is not an integer" does not mean Fe is 0

Fe can be +2 or +3 in compounds, and 0 as an element.

S is -2 in compounds

Fe3S4

4 S = -8

3 Fe = +2.667

If you had 2 Fe+3 and 1 Fe+2 you would have +8

Fe2S3 and FeS would be Fe3S4

Answer 3

S 2-, not S 2+.

Fe3O4 (magnetite) is similar.

Look up magnetite in Wikipedia. You will see that it contains iron in two different kinds of environment.  Take it from there.

Answer 4

Sulfide ion comes in the form of S 2-. You have:

Fe3S4

Or: (3 x 2.666 repeating) + (4 x -2) = 0