Britannica Educational Publishing 
Matter [PDF ebook] 

The diversity of the various states of matter-solids, liquids, and gases-belies their essential similarities. All matter is composed of atoms that combine in different ways, giving us the multitude of shapes and structures we observe on a daily basis. Readers examine the different states and properties of matter, as well as the laws and forces to which matter is subject. Annotated diagrams provide visualization of complex concepts.