Structure of The Atom
Study Points
- Democritus, Greek Philosopher in 400 BC named the smallest piece of matter “ATOMOS ,” meaning “not to be cut.”
- Dalton's theory (1803) was based on the premise that the atoms of different elements could be distinguished by differences in their weights.
- WIth the invention of Scanning Tunneling Microscope we can see atoms.
- Electrons, protons and neutrons are the fundamental particles of an atom.
- Electrons were discovered by JJ Thomson in discharge tube experiments as cathode rays.
- Cathode rays are streams of negatively charged particles.
- They are deflected by electric and magnetic fields.
- The specific charge of electron was determined by J. J. Thomson
- The charge of the electron is 1.602 x 10-19 coulombs.
- The absolute mass of electron is 9.108 x 10-28 g or 9.108 x 10-31kg
- Protons are positive rays that were discovered by Goldstein in the discharge tube experiments when perforated metal cathode was used.