## 9.25

Boltzmann Equation for Entropy: $S = k_{B} \ln W$

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Jade Fosburgh Discussion 2C
Posts: 59
Joined: Fri Sep 29, 2017 7:07 am

### 9.25

Is there a general rule to figuring out how many possible arrangements an atom can have based on its lewis structure?

In 25 we are given the molecule SO2F2. The lewis structure is tetrahedral but has 6 possible orientations. I am having trouble visualizing the orientations and figuring out the number of orientations for different molecules (trigonal planar, octahedral, etc.)

Sungyoon_Baek_1A
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### Re: 9.25

Im not sure if there is a general rule since even though two molecules may share the same shape, if they are composed of different atoms they may not share the same number of arrangements (for example CH4 is also a tetrahedral but only has one possible arrangement since all the atoms bonded to the central carbon atom are the same). However, to help you visualize the orientations, I recommend drawing out the possible arrangements. For example, I started off with the oxygens on the left and top (of the sulfur) and the fluorines on the bottom and right. Then just keep going around rotating the atoms around until you can no longer make any more possible combinations. So we could have: oxygen on the left and right and fluorine on the top and bottom; oxygen on the left and bottom and fluorine on the top and right; flouring on the right and left and oxygen on the top and bottom; flouring on the left and top and oxygen on the right and bottom; and lastly oxygen on the top and right and flouring on the left and bottom. So after drawing all of these arrangements we see that there are 6 possible arrangements for this molecule.

rkusampudi
Posts: 58
Joined: Fri Sep 29, 2017 7:04 am

### Re: 9.25

I think the simplest approach is to look at the shape of the molecule as well as the number of different elements involved (e.g. switching the positions of two oxygens doesn't count as a different arrangement). Here there are four atoms around the central sulfur atom and they are of two types

Vanessa Romero-Campos 2B
Posts: 39
Joined: Fri Sep 25, 2015 3:00 am

### Re: 9.25

Would we have to accurately draw the molecule with wedges and dashes to depict the 3D structure of the molecule or would it not matter?

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