Atkins' 4 Laws that Drive the Universe: Chapter 3 notes

Where we are so far:

The zeroth law necessitated the definition of a property called, temperature, T, a parameter for the distribution of energy within a system of particles at equilibrium ("relative populations fo the differenet energy levels of particles in a system at equilibrium"; "turmoil and temperature go hand in hand" is a useful mnemonic).

The first law brought about the definition of a quantity called the internal enrgy of a system ,U

The second law implies the existence of a property called entropy S

Useful summarization contrasting energy and entropy:

"...whereas U is a measure of the quantity of energy that a system possesses, S is a measure of the quality of that energy: low entropy means high quality, high entropy means low quality."

To be continued...

Atkins' discussion of both the Kelvin and the Clausius phenomenological, or observation-based, statements could use a little more clarification.  I understand that what he was trying to do was to lead up to the more familiar statement of the second law (the entropy of the universe increases during a spontaneous process).  I did not think that he defined what spontaneous means precisely.

In this chapter, he repeats a good summarization of the first and second law that is found in his P. Chem. textbook:

"The first law and the internal energy identify the feasible change among all conceivable changes: a process is feasible only if the total energy of the universe remains the same.  The second law and entropy identify the spontaneous changes among these feasible changes: a feasible process is spontaneous only if the total entropy of the universe increases."

Good analogy of the inverse propotionality between change in entropy and its direct proportionality to energy released or absorbed:  sneezing in a quiet library has more impact than sneezing in a loud busy street.