Wednesday, 26 November 2008

S205: Book 4 - Metals and Chemical Change

So book 4. This one is all about why reactions happen. Why do some things when you mix them together react, some require heating, and some just never bother.
It has the potential to be a very boring book, as it discussing a lot of stuff about entropy, enthalpy and Gibbs free energy.
There are a number of videos that accompany the book and help bring it to life a little. Some of the chemical equations and calculations I find a little confusing, especially around metal ions. The crown ether stuff is also a little esoteric I found, but in the end with a bit of practice its possible to make some sense of the calculations.
Its quite interesting to see that given all this detail you can make some predictions about what reactions are possible and which aren't.
However all thats said there is a lot of equation manipulation in this bit - all relatively simple but there are enough steps that its really easy to miss off a coefficient here, or a plus sign there.

The book wraps up with a case study on batteries which is quite interesting. Going into the details of dry cells, NiCd and so on giving the design decisions around each.

Friday, 14 November 2008

S205: Book 3 - The Third Dimension

Book 3 is a little weird, it is actually two books it seems to me.

Part 1 looks at crystals in some depth.
It goes through the various forms of crystal structures that can be made, and looks at ionic bonding that is prevalent in crystals.
I found this quite hard going, there is a lot of 3-d visualisation to get the ideas, but its not always easy as there is a lot going on in some of the structures. Trying to work out the common patterns is not easy, and I found the 3-d visualisation software though good, didn't really help as it lacks a good perspective. You get to make one or two models too, which sometimes helps, but the complex ones can't be made. There are a number of videos also showing you how they are constructed, so you can't fault them for trying - but really none of it made much sense to me until the tutorial.

Part 2 looks at stereochemistry, and chirality.
First it starts by looking at the effect double bonds can have on structure. Because double bonds stop the free rotation of molecules, you can have two different forms of the same molecule, and then you get into the whole "how do you name them" discussion. Having worked through this and got some rules on exactly how to name things which look different but have the same components, you get into chiral chemistry. This is where typically a carbon has 4 different things attached to its different bonds, and this allows two possible configurations of the molecule. These structures also have interesting optical properties as they rotate polarised light.
However it doesn't end there, as you can have molecules with more than one chiral center, and then things get really complicated with stereo isomer, diastereomers, entaniomers, and meso formations. If crystals gave you a headache, well you haven't felt anything yet!

Finally the book finishes up with a case study on liquid crystals.

Monday, 10 November 2008

S205: Book 1 and 2

I have to say the chemistry books are slightly confusing at first.
Book 1 and 2 for this course are actually two sections of a single physical book.
Book 1 - or sub-book1 - is entitled "A prologue to the course" and is more or less what it says. Its presumably designed to suck you into the chemical world as it describes the great successes and progress that has been made in chemistry over the last few hundred years.
It covers diverse applications from forensics to ball lightning and mostly its just an enjoyable read - nothing too heavy anyway.

Then the second half of the book is "An introduction to the molecular world" gets into more details of chemistry. It looks at periodicity, electron configuration, VSEPR, bonding and reactivity. Its not too heavy, but the course has definitely begun in this book. Some of the topics covered, such as the VSEPR theory and the different types of bonding are useful. The idea that a noble gas configuration is not always required is a little disturbing in some ways, but one of the deeper truths that you have to contemplate.