INTRODUCTION the object weighs more at the surface than it does atop the mountain even though its mass has not changed People s understanding of matter has grown over the years For centuries scien tists were sure that matter and energy were two separate things Yet as Albert Einstein proved with his theory of special relativ ity better known as E mc the two are so closely linked that they are said to be equivalent In fact matter can be converted to energy and energy can be converted to matter Beyond special relativity there have been other theories of matter raised in the modern era The rise of quantum mechan ics the study of matter at the atomic and smaller levels astronomical observations and experimentation in particle physics each have revealed plenty about the nature of mat ter No doubt more theories will come in the I future as scientists continue to investigate the fundamental topic of matter
CHAPTER 1 THE BUILDING BLOCKs OF MATTER n electron a grain of sand an ele phant and a giant star at the edge of the visible universe all have one thing in common they are composed of matter which is the material substance that makes up the physical universe A beam of light the motion of a falling stone and the explosion of a stick of dynamite also have one thing in common they are expressions of energy Together energy and matter form the basis for all observable phenomena Matter is made up of tiny units known as atoms molecules and ions Atoms are the basic building blocks of chemistry An atom is the smallest piece of matter that has the char acteristic properties of a chemical element such as hydrogen oxygen calcium iron gold and neon More than 90 types of atoms exist in nature one a and each forms different ele ment Though elements are made up of only IO
THE BUILDING BLOCKS OF MATTER е о с E oD C Doo c OOO Water filling a glass beaker A huge number of water molecules not to mention bydrogen and oxygen atoms are needed to fill a container such as this iStockphoto Thinkstock II
