The study of chemistry will open your eyes to a fascinating world. Chemical processes are continuously at work all around us. They happen as you cook and eat food, strike a match, shampoo your hair, and even read this page. Chemistry is called the central science because a knowledge of chemical principles is essential for other sciences. You might be surprised at the extent to which chemistry pervades your life. 1.1: What Is Chemistry? Chemistry is the study of matter—what it consists of, what its properties are, and how it changes. Being able to describe the ingredients in a cake and how they change when the cake is baked is called chemistry. Matter is anything that has mass and takes up space—that is, anything that is physically real. 1.2: The Classification of Matter Matter can be described with both physical properties and chemical properties. Matter can be identified as an element, a compound, or a mixture. 1.3: Measurements Chemists measure the properties of matter and express these measurements as quantities. A quantity is an amount of something and consists of a number and a unit. The number tells us how many (or how much), and the unit tells us what the scale of measurement is. For example, when a distance is reported as “5 kilometers,” we know that the quantity has been expressed in units of kilometers and that the number of kilometers is 5. 1.4: Expressing Numbers - Scientific Notation Scientific notation is a system for expressing very large or very small numbers in a compact manner. It uses the idea that such numbers can be rewritten as a simple number multiplied by 10 raised to a certain exponent, or power. Scientific notation expressed numbers using powers of 10. 1.5: Expressing Numbers: Significant Figures Significant figures properly report the number of measured and estimated digits in a measurement. There are rules for applying significant figures in calculations. 1.6: The International System of Units Recognize the SI base units. Combining prefixes with base units creates new units of larger or smaller sizes. 1.7: Converting Units The ability to convert from one unit to another is an important skill. A unit can be converted to another unit of the same type with a conversion factor. 1.E: Exercises These are homework exercises to accompany Chapter 1 of the Ball et al. "The Basics of GOB Chemistry" Textmap. 1.S: Chemistry, Matter, and Measurement (Summary) To ensure that you understand the material in this chapter, you should review the meanings of the bold terms in the following summary and ask yourself how they relate to the topics in the chapter. Thumbnail: Two small test tubes held in spring clamps. Image used with permission (CC BY-SA 3.0; mitchell125 ).