Identify the chemical symbols for a number of elements. An atom is a tiny particle.
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Atoms are far too small to see with only a light microscope. Scientists have to use very powerful electron microscopes to get a closer look at atoms.
Early Ideas About Atoms
Over time, scientists have gained a greater understanding of the structure of atoms.
More than 2,000 years ago, some Ancient Greeks suggested that everything was made up of four elements: earth, air, fire and water. However, they did not investigate this idea scientifically.
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Outline how our understanding of matter has evolved over time. Explain what an element is.
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Key Words Atom
Element Chemical symbol
Learn more about electron microscopes in Biological World 1.3
Over 200 years ago, the chemist John Dalton developed a theory about atoms. Unlike the Ancient Greeks, Dalton based his ideas on investigations he carried out.
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Dalton was the first to suggest that everything is made up of tiny particles called atoms.
Dalton also suggested that some substances are made up of atoms that are the same as each other.
Dalton was able to use his theory to explain the wide variety of substances on Earth. He stated that atoms could join together in different ways to make new substances.
Thanks to Dalton’s theory, we now have a very simple and useful definition of an element.
