The Kingfisher Book of 1001 Wonders of Science [antikvár]

ATOMS ATOMS What is an atom? An atom is the smallest unit of a chemical element - iron or copper, for example - to have its own recognizable identity. Scientists can teil the atoms of one element from those of another by their structure. Atoms are the building blocks of the elements which make up all matter in the universe. What does the word atom mean? The word 'atom' comes from the Greek word atomos, meaning 'uncuttable'. The scientists of Ancient Greece thought that an atom was the smallest thing that existed: it could not be divided. Modem scientists, by Splitting the atom, showed that this is not so. But the atom is the smallest unit that behaves as a stable chemical element. IJan atom was as big as yourfingernail, your hand would be huge. How big is an atom? Atoms measure approximately one millionth of a millimétré across. So a page of this book is about two million atoms thick! If an atom were the size of your fingernail, your hand would be large enough to pick up the Earth. How is a tiny atom like the entire solar system? Atoms are made up of tiny particles moving around a centre called the nucleus. This is very like the way in which planets in our solar system orbit the Sun. Boron atom