Nuclear Chemistry Review

Radiation

  • There are two types of radiation: electromagnetic and nuclear radiation
  • Radioactive isotopes become stable by ejecting matter and/or energy
  • Acute exposure: When lots of ionizing radiation hits us in a short time period and can mutate and/or kill cells

Review

  • Isotope: Atoms of the same element with different mass numbers

Radioactivity

  • Radioactivity: the process by which substances spontaneously emit rays and particles

Chemical Reactions

  • In chemical reactions, atoms attain a stable electron configuration by losing or sharing electrons
  • Chemical reactions are Affected by changes in temperature, pressure, or the presence of catalysts
  • Chemical reactions release less energy than nuclear reactions

Nuclear Reactions

  • In nuclear reactions, the nucleus of an unstable isotope gains stability by undergoing changes
  • Unlike chemical reactions, nuclear reactions aren’t affected by changes in temperature, pressure, or the presence of catalysts
  • Nuclear reactions of an isotope cannot be sped up, slowed down, or turned off
  • Nuclear reactions Release massive amounts of energy

Radioactive decay

  • Radioactive decay: process by which an unstable nucleus emits radiation and energy in order to obtain a more stable state.
  • Alpha radiation:
    • Alpha radiation Consists of helium nuclei
    • Alpha radiation Contains 2 protons, 2 neutrons, and has a positive 2 charge
    • Alpha particles are unable to travel far
    • Alpha radiation Cannot penetrate well; a sheet of paper or the surface of skin stops them
  • Beta radiation:
    • Beta radiation Results from the breaking apart of a neutron into a proton and an electron
    • Beta radiation Has less mass than an alpha particle
    • Beta radiation Passes through paper, but it’s stopped by foil or wood
  • Gamma radiation
    • Gamma radiation: A high energy proton emitted by a radioisotope
    • Gamma radiation has No mass or charge
    • Gamma radiation Easily passes through paper, wood, and the human body
    • Gamma radiation Can be blocked by several centimeters of lead

Nuclear Stability

  • Nuclear stability depends on it’s neutron:proton ratio
  • Number of neutrons vs. number of protons for each element resulting in a region creates the Band of Stability
  • All nuclei that have an atomic number greater than 83 are radioactive

Half-Life

  • Half life: the time required for half of the nuclei of a radioisotope sample to decay to products

Transmutation

  • Transmutation: the conversion of an atom of one elect to an atom of another element
  • Transmutation occurs in two ways: radioactive decay and when the nucleus of an atom is bombarded with certain types of particles
  • Particle notation:
    • Alpha: 4/2He
    • Beta: 0/-1e
    • Gamma: 0/0y
    • Neutron: 1/0n
    • Proton: 1/1H
    • Positron: 0/1e

Transuranium Elements

  • Transuranium Elements: Elements in the periodic table with atomic numbers above 92
  • All Transuranium elements undergo transmutation, do not occur in nature, and are synthesized in the laboratory

Nuclear Fission

  • Fission: A neutron slams into a larger atom (U-235), forcing it to split into 2 smaller atoms (Ba-141 and Kr-92), 3 neutrons, and energy

Nuclear Fusion

  • Fusion: 2 small nuclei merge to form a larger nucleus with a greater mass, releasing energy and a neutron
  • Fusion reactions require very high temperatures to complete