ABSTRACT
Chemistry is unique – among the traditional triad of biology, chemistry, and physics – in that the objects chemists study (atoms and molecules) cannot be directly observed. Given the inherently small size of atoms and molecules, the numbers that chemistry uses tend to be very large or quite small. This chapter starts by reviewing the basics of scientific notation (and the related E notation used by computers and calculators). From there, the chapter moves on to a discussion of measurement, precision, and accuracy. Given that all measurements involve a degree of estimation, we must have a way of properly accounting for the quality of a number. Significant figures are the system for accounting for measured values. The conventions for determining significant figures and properly reporting calculated values using significant figures are covered with substantial practice given throughout. Finally, the chapter concludes with an introduction to the basics of the International System of Units (SI) and the common SI prefixes.
