atomic structure

• what is the radius of an atom

  1 x10-10
• what is the radius of a nucleus

  1x10-14
• what is the atomic number

  number of protons
• what does dalton say

  atoms are spheres
• what does thomson say

  plum pudding model -a postive ball of charge with negative electrons embedded in it
• what does rutherford say

  gold foil experiment -positive nucleus
• bohr

  electrons orbit in shells
• chadwick

  neutrons
• what is radioactive decay

  unstable nuclei emit radiation to become more stable .It is a random process so you cant predict it
• what is alpha radiation made out of

  2 protons and 2 neutrons (helium )
• alpha radiation

  low pentrating power

  high ionising power
• what is alpha radiation stopped by

  paper
• what is beta radiation made of

  electron
• beta radiation

  medium ionising

  medium penetrating
• what is beta radiation stopped by

  5 mm of aluminum
• what is gamma radiation made of

  electromagnetic wave
• gamma radiation

  high penetrating power

  low ionising power
• what is half life

  time it takes for half of the unstable nuclei to decay

  time it takes for the count rate to half
• what is half life measured in

  becquerels
• what does you use to measure radiation

  geiger muller tube

  measured in counts per seconds or bq

  always subtract the background radiation
• radation can ionise cells leading to

  mutations

  cell death
• what is irradiation

  being exposed to radiation but object not radioactive
• what is contamination

  object exposed to radiation and becomes radioactive
• how to protect against radiation

  lead shielding ,limit time ,use tongs
• what radiation does medical tracers, radiotherapy ,sterilizing equipment

  gamma
• what radiation does thickness control use

  beta
• what radiation does smoke alarms use and why

  alpha

  -ionises air but blocks smoke
• what is nuclear fission

  splitting of large unstable nucleus ,triggered by a slow neutron
• what does nuclear fission release

  • energy
  • 2 or 3 neutrons
  • radioactive products
• what reaction does nuclear fission cause

  chain reaction
• what is nuclear fusion

  two light nuclei combine to make 1 heavier nucleus
• how is nuclear fission different from nuclear fusion

  nuclear fusion uses more energy and happens in extreme temps and pressure