# Homework Help: Bismuth sulphide structural diagram

1. Nov 3, 2005

### PhysicBeginner

Can anyone tell me if the structural diagarm of Bismuth(III) Sulphide looks like this:

S-S-S
l l
Bi = Bi

2. Nov 3, 2005

### rocketboy

They want to have a total of 40 electrons.
They have a total of 28.
That leaves a difference of 12 e-, divide by 2e- per bond, meaning there are going to be 6 bonds.
The structural diagram would look like this (i think).

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3. Nov 4, 2005

### Gokul43201

Staff Emeritus
That's a good attempt, rocketboy...but I don't think it's the right structure. For one thing, it creates too many charged species (with the central S-atom having to accomodate a 2+ charge)

I can think of a structure that requires only two singly-charged species.

PhysicsBeginner : It's an important part of the process that you figure out the charges on the different atoms. To do this, you must also determine the number of non-bonding electrons on each atom.

The failure of your structure lies in the following :

1. It requires 4 charged atoms (and it requires an S to hold a positive charge and a Bi to hold a negative charge; both of which are against their tendencies)

2. It proposes a long, linear molecule, which is energetically less favorable than a more compact structure, like the one suggested by rocketboy.

3. There's a structure that is more compact still, and yet has only 2 charged species (an S- and a Bi+).

Last edited: Nov 4, 2005