Most of the science that I know I learned from reading the science books of Isaac Asimov. For years, he wrote a monthly essay in "Magazine of Fantasy and Science Fiction" covering a scientific topic and they contain some of the most elegant of explanations of scientific principles. Asimov has often been accused of oversimplifying his explanations, but as someone who has taught math and computer science for years at the college level, that is pretty hard to do. The goal is to have the students learn and any method that works is one to consider using.
This book is a collection of seventeen of his essays that appeared in F&SF and as usual they cover a smorgasbord of topics. The essays are split into four categories:
*) Physical chemistry
They are a combination of the history of scientific discovery and speculation about future results. Since the book was published in 1987, there are points that have been superseded by events. The most evident case is essay fifteen, "The Rule of Numerous Small." In this essay, Asimov discusses the current evidence for how numerous planets are. Recent advancements in planetary detection techniques have rendered some of what he says obsolete.
Nevertheless, there is no one better than Asimov at making science understandable. Since understanding is almost always a process of successful small steps of comprehension, it is always better to start simple and work your way up. Asimov's writing remains the best initial step in scientific understanding that I have ever encountered.