Question

What determines electronegativity? How can I, given a certain type of atom, calculate it with no prior experimental knowledge of it?

Answer 1

You can't. Electronegativity is an empirical quantity, a short-hand number that is meant to encapsulate a wide variety of chemical behaviour in a single approximate quantity. Think of it as like the rankings of sports teams, or the "score" a political lobbying organization might give legislators on their favorite issue. It's just a way to sum up metallic versus nonmetallic behaviour in a form that suggests the size of the differences between elements. It cannot be relied upon quantitatively.

That said, you can certainly look up any of the various defiitions of electronegativity, and work from there. The Pauling electronegativity, for example, is calculated from bond energies, and in principle you could calculate these from first principles (i.e. from quantum chemistry calculations on a big computer). It's unlikely the state of the art is good enough to do better than experiment, except for the lightest elements.

Answer 2

Chemistry is so complex! Thank you.

By the way, can you recommend any good (preferably free and online) books on physical chemistry?

Answer 3

Things that are free are generally worth what you pay for them, so no, I have no recommendations of free books.

My preferred undergraduate physical chemistry textbooks are:

"Physical Chemistry," by Atkins and de Paula:

http://www.amazon.com/Physical-Chemistry-Peter-Atkins/dp/1429218126/

"Physical Chemistry," by McQuarrie and Simon:

http://www.amazon.com/Physical-Chemistry-Molecular-Donald-McQuarrie/dp/0935702997/

You can also try the books by Raymond Chang, by Silbey and Bawendi, and by Castellan, which are older but more classic texts.

None of them is particularly easy to read. McQuarrie tends to be the clearest and precise, while Atkins tends to be creative and illuminating. Chang focusses on biological applications. Silbey and Castellan are very strong on thermo, while McQuarrie is very strong on quantum and Atkins on statistical mechanics.

Answer 4

Fair enough- I have found some good mathematics texts in the past, though. I'll be sure to look them up.

Answer 5

If you are not required to get the textbook for a class, the obvious thing to do is get an edition two or three before the current edition. These can often be had at rock-bottom prices, because students are trying to unload their copies, and students who are taking the course are required to buy the latest edition (a giant scam, but that's another story).

Since the textbooks change very little between editions, if you are doing any kind of self-study, an edition from 5 or even 10 years ago is perfectly fine, and you get almost all the benefit of the quality book without the price. All you're missing are some minor essays on current applications, some updated drawings, some corrections to problems, and so forth. Piddling stuff.