What is an atom Building blocks All the objects you can see and feel around you your chair this book your clothes and even you yourself are made of billions of tiny atoms Atoms are the building blocks of matter They are what stuff all stuff is made of As you know there are different types of matter from wood to water paper to plastic stone to steel All these things are made of different types of atoms either on their own or in combination with other atoms All the objects and people you see around you are made up of billions and billions of tiny atoms The atoms join together in different patterns to make molecules which make up millions of substances What is matter Matter is all the materials and objects and substances around us including solids liquids and gases Not everything is matter for example light and sound are forms of energy However as scientists have discovered matter and energy are closely related and one can be turned into the other There are more than 100 types of atoms which make basic substances known as elements For example gold oxygen and iron are elements each made of just one type of atom But combined with each other the basic atoms make the millions of different substances and materials we see all around us 6
Atoms and molecules 1 H H Hydrogen molecules H H O O Oxygen molecule 2 H H H H Hydrogen atoms O O Oxygen atoms 3 H O H H O H Water molecules How small Atoms are really really tiny You cannot see individual atoms with the naked eye They are so small that 100 million atoms all lined up in a row would only reach across your little fingernail Splitting the atom It took many years to discover and understand atoms At first people believed that atoms were the smallest unit of all and that something so tiny could not be split into smaller parts But during the 20th century scientists learned otherwise They found that they could split atoms apart And what they discovered led to some hugely powerful and dangerous results In this book you'll find out how the atom was split and what it meant for all our lives Oxygen and hydrogen atoms join together in pairs to make molecules of pure oxygen and hydrogen 1 They can also split apart 2 and join with other atoms One oxygen atom joined to two hydrogen atoms makes a water molecule 3 THAT’S A FACT When you look at or touch any object you’re seeing or feeling billions of atoms packed together For example a page in this book is about one million atoms thick and one glass of fruit juice contains about 25 trillion trillion 25,000,000,000,000,000,000,000,000 atoms 7
