Unstable Nuclei & Radioactive Decay

Chemical reactions involve changes in the electrons surrounding an atom. Nuclear reactions involve changes in the nucleus of an atom.

Radioactive atoms emit radiation because their nuclei are unstable. Unstable nuclei lose energy by emitting radiation in a spontaneous process called radioactive decay.

Review of Terms Isotopes - atoms of the same element with different mass numbers (different numbers of neutrons) Radioisotopes - isotopes of an element that radioactively decay (are unstable) Radioactive decay – the process through which an unstable nucleus changes into another more stable nucleus by giving off a particle and some radiation Radiation – energy that can be transmitted through a vacuum in the form of a wave Examples: light, X-Rays, UV Rays, IR Rays, Gamma Rays, Radio Waves

What elements are radioactive? Occur in Nature 84 – 92 (Polonium – Uranium) Made in a Laboratory 43(Tc), 61(Pm), 93 – 116 (as of now)

Nuclear Equation Shows the atomic numbers and mass numbers of the particles involved.

Alpha α Contains 2 protons & 2 neutrons. Alpha Particle has a - Mass of 4 and a Charge of +2 Fairly large particle; doesn’t penetrate well (paper can stop it)

What is an alpha radiation? https://www.youtube.com/watch?v=j5TJRtJxVfs

Beta β Each beta particle is an electron with -1 charge. Therefore a beta particle has a charge of -1 Small particle; moves at close to the speed of light; requires 1-2 in. of metal to stop

What is beta radiation? https://www.youtube.com/watch?v=rW0A5FZTxt0

Gamma γ High energy radiation that posses no mass Because they are neutral, gamma rays are not deflected by electric or magnetic fields.

Video: Radiation and Radioactive Decay https://www.youtube.com/watch?v=oFdR_yMKOCw

Half - Life The amount of time it takes for one-half of a given mass or number of atoms to decay

Video: Carbon Dating https://www.youtube.com/watch?v=2io5opwhQMQ

Applications of Nuclear Chemistry How was Radiation Discovered? Wilhelm Roentgen (1895) - discovered X-Rays Henri Becquerel (1896) - found that Uranium emits radiation onto photographic film - X-Rays Marie and Pierre Curie (early 1900’s) - found Radium (another radioactive element) and Polonium Found it ionized air particles and made phosphorescent objects glow Found that when radiation is emitted, other elements are then created Also found radiation causes severe health effects (They both died of cancer) Ernst Rutherford (1912) – gold foil experiment; discovered the nucleus

Nuclear Bombardment Reactions Ernest Rutherford first did this in 1919 Particle Accelerator - Basic Idea: Particle accelerators use a series of magnets to create a path that the nuclei must follow (nuclei are positively-charged, so they interact with magnets). When a collision is desired, the orientation of the magnets is changed to change the path of the nuclei; two types: Linear Accelerator – straight path, particles can get to about 90% speed of light Tevatron – “big donut”; only a few in the USA – 99% speed of light

Video: Nuclear Reactions https://www.youtube.com/watch?v=50RWvXmQcFk&list=PL43285691048DAD00&index=18

CERN: Super Collider https://www.theguardian.com/science/video/2015/feb/03/large-hadron-collider-cern-scientists-second-run-particle-accelerator-video

Nuclear Reactors http://www.compoundchem.com/2016/04/26/nuclear-reactors/ How Do Nuclear Power Plants Work? https://www.youtube.com/watch?v=PKNbwcIaGng What went wrong at Chernobyl? https://www.youtube.com/watch?v=DOWD0CBxE7w

Current Events Submit via socrative… Room #335755 What happened in Fukushima Japan? Find 2 nuclear power plants near MI When were they built? What could happen to you if a disaster were to occur?