Matter

Matter — page 5 — 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

Matter — page 6 — 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

Matter — page 7 — MATTER one type of atom gold contains only gold atoms and neon contains only neon atoms other substances are mixtures of different kinds of atoms Atoms also join together chemically to form molecules Ions are elec trically charged atoms or groups of atoms All atoms are roughly the same size About 50 million atoms of solid matter lined up in a row would measure only 0 4 inch 1 centimeter Since atoms molecules and ions are very small the bulk matter of everyday life consists of large amounts of these components A glass of water for instance contains an extremely large amount about 8 x 1024 of water mole cules Each water molecule is in turn made up of two hydrogen atoms and one oxygen atom that have been combined chemically ATOMS Scientists long believed that atoms were ele mentary particles that had no discernible structure and could not be broken apart In fact the word atom comes from a Greek word meaning indivisible Since the end of the 19th century however it has been known that atoms are themselves made up of smaller particles It requires a great deal of energy to break an atom into its component parts 12

Matter — page 8 — THE BUILDING BLOCKS OF MATTER Helium Carbon e e nucleus O proton O neutrone electron The positively charged nuclei of belium and carbon consisting of protons and neutrons are circled by negatively charged electrons Encyclopaedia Britannica Inc 13

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