Investigating atoms

Investigating atoms

1. How ideas about atoms have changed

   • All matter consists of atom, which cannot be divided up.
   • All atoms of the same element are identical, but different from atoms of every other element.
   • The Greeks suggested the idea of atoms in the 5th century BC, John Dalton revived the ideas in the 19th century.
   • In 1897 the electron was discovered, 1909 the nucleus was discovered, 1911 Rutherford suggested that electrons orbit the nucleus, 1919 protons were discovered, and 1932 neutrons were discovered.