atoms and radiation

• atoms size is about 1x10^-10m
• the nucleus contains the most mass of an atom
• overall charge of a nucleus is positive
• Rutherford discovered the nucleus and that electrons surround the nucleus
• J.J Thomson's discovery was the Plum Pudding Model 


  A ball of positively charge with negatively charged electrons mixed in with the 'dough'
• Niels Bohr discovered that electrons orbit the nucleus in fixed positions
• If atoms absorb electromagnetic radiation the electrons move to a higher energy level which is further away from the nuclues
• If atoms emit electromagnetic radiation the electrons drop to a lower energy level and move closer to the nucleus
• Isotopes are atoms with the same number of protons but different number of neutrons