[mike]

I would like to know what people think the answer to this question is and why:

Which one of the following compounds has the least ionic character?
 
a. Bismuth sulfide
b. Bismuth iodide
c. Bismuth fluoride
d. Bismuth bromide

Now I know the rules say not to post questions without having attempted the answer yourself. I do have an answer for this question which I will post, however I did want to hear some other peoples opinions before mine.

Also I have posted the question here as I thought it may be useful for chemistry students to read peoples answers and thoughts.

Let me know what you think

[Yggdrasil]

Probably the quickest answer is just to look up the electronegativities and choose the compound with the smallest difference in electronegativities (bismuth sulfide).  A more comprehensive answer would probably require using a quantum chemistry program to simulate the charge and electron distribution of the compound and choosing the one with the most equal electron distribution between the bismuth and anion.

[Albert]

I agree with Yggdrasil: I would look at the electronegativity and answer bismuth sulphide.