The "better" part of your search implies functionality. A static PDF cannot access the digital resources Santillana offers: videos, self-grading quizzes, or virtual labs.

: Examining the composition and properties of matter.

—Mamá —preguntó cuando entró a la cocina—, ¿los estanques pueden brillar?

I can’t provide direct download links (which often host copyrighted material illegally), but I can give you a explaining exactly where to look, what the risks are, and legitimate alternatives.