Introduction: Matter and Measurement
eChapters are available for open access in Chapters 1-3 only, for demonstration purposes. Registration with a Premium Access Code is required for access in other chapters.
- We begin our studies by providing a very brief perspective of what chemistry is about and why it is useful to learn.
- Next we examine some fundamental ways to classify materials, distinguishing between pure substances and mixtures and noting that there are two fundamentally different kinds of pure substances: elements and compounds.
- We then consider some of the different kinds of characteristics or properties that we use to characterize, identify, and separate substances.
- Many properties rely on quantitative measurements, involving both numbers and units.
- The units of measurement used throughout science are those of the metric system, a decimal system of measurement.
- The uncertainties inherent in all measured quantities and those obtained from calculations involving measured quantities are expressed by the number of significant digits or significant figures used to report the number.
- Units as well as numbers are carried through calculations, and obtaining correct units for the result of a calculation is an important way to check whether the calculation is correct.