9781422279489

Oxygen: INTRODUCTION

Introduction

H ave you felt a breeze on your face today? Drank a nice, cool glass of water? Lit a sturdy match and watched the glow of a campfire? All of those things—the sol- ids, liquids, and gases around you—are composed of elements of the periodic table. The periodic table is an arrangement of all the naturally oc- curring, and manufactured, elements known to humans at this point in time. An element is a substance that cannot be broken down into other, separate, substances. There are 92 elements that can be found naturally on Earth and in space. The remain-

WORDS TO UNDERSTAND isotope an atom of a specific element that has a different number of neutrons; it has the same atomic number but a different atomic mass

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