Atomic structure

• IN ancient greece , there was two main ideas , first one was that an element could be cut forever , and the other one was that an element had a smallest 'building black ' they called it Atom ( A= can not , Tom = cut = can not be cut)
• In 1805 , John Dalton said that

  • All matter is made of tiny particles called atoms
  • Atoms are tiny hard spheres that cannot be broken down into smaller particles
  • Atoms cannot be created nor destroyed
  • The atoms in an element are identical but each element has its own type of atoms
• • In 1897 , Joseph John Thomson ( 1856-1940) discovered a negatively charged particle , which he called electron .
  • Thomson noted that Dalton's model ( theory ) didn't include the idea of charge.
  • Thomson supported the 'plum-pudding' atomic model which indicated that there were pockets of negative charges within the sphere of the atom
  • Thomson's model was inherently stable ( if the electrons were displaced , they would attempt to return to their original position)
• Rutherford atomic model (1911)

  • Ernest Rutherford ( 1871-1937) , in cooperation with other scientists performed alpha practice experiment that led to the overlurning of T's model
  • Regarding the experiment's results , Rutherford conclude that there must be a small , highly dense core of matter in an atom off which the alpha particles were bouncing , the nucleus .
  • He theorized that this nucleus was positively charged and sumrised that electrons orbited around it .
  • The model suggested that the charge of the u