1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Ionizing Radiation and Electron Emission

  1. Oct 11, 2014 #1
    Can someone clarify what Ionizing Radiation is and how it relates to Alpha, Beta, and Gamma Emission and/or Absorption?

    A question in the Princeton Review Science Workbook read:

    The daughter nucleus of CS-137 is:...

    and the answer is 137 - Barium.

    The text says that Alpha, Beta, and Gamma Particles are destructive because of their ability to ionize atoms they collide with.

    So this suggests (given the answer to the question) that the Ionizing Abilities of such radiation (alpha, beta, and gamma particles/radiation) can cause a neutron to break open and release an electron, thus leaving an extra proton (this is how CS-137 became Ba-137. Barium has 1 more proton than Cesium and Ba-137 has the same mass).

    But in doing some side reading, I found that Alpha , Beta, and Gamma particles induce ionization by exciting electrons they collide with. This is different from breaking open a neutron. Can anyone clarify?
  2. jcsd
  3. Oct 11, 2014 #2


    User Avatar
    Science Advisor
    Gold Member

    Your sources seem to be all over the place...

    "Ionizing radiation" is used to denote any radiation (alpha, beta, gamma, neutron, etc.) which is energetic enough to break the molecular bonds in your body and be harmful to you. Molecules are held together by chemistry, and chemistry is basically just how the outer shell of electrons in atoms arrange themselves so that bonds between atoms can form. If your radiation is strong enough that it can ionize atoms (i.e. remove atoms of electrons), then it is strong enough to break up (some) molecular bonds. It has nothing to do with "breaking up neutrons". The reason we split radiation into "ionizing" and "non-ionizing" radiation is that "radiation" by itself really just means particles in motion, it's a pretty blanket term (mostly for historical reasons). Usually radiation would imply that these "particles in motion" came from some sort of nuclear reaction, but it doesn't always have to be. Light, for example, is a form of radiation, just like the electrons in beta decay, the helium nuclei in alpha decay, or the individual neutrons in neutron emission, are radiation. The light from your computer is a form of radiation. It is non-ionizing radiation, and so it will not harm you. Ionizing radiation, like gamma rays, or high-energy alpha/beta particles or neutrons, WILL hurt you if you receive a significant enough dose.
  4. Oct 11, 2014 #3
    Okay thanks a lot. I think i got confused because you hear of "Ionization" in chemistry when an atom is hit with radiation to eject an electron.

    I think I was/am confusing decay vs ionizing radiation.

    Decay [can] result in a neutron breaking apart to release a beta particle, and a beta particle can be an electron.

    But ionizing radiation causes electrons to be ejected. When we speak of ionizing radiation is it the same radiation we speak of when it comes to ionization energy? In biology, is it the same idea but applied to bonds? I guess only looking at ionization at the atomic level (on a single atom basis) I neglected to consider that ionization could apply to bonds as well. Am i on the right track?
  5. Oct 11, 2014 #4


    User Avatar
    Science Advisor
    Gold Member

    A beta particle IS an electron. Beta decay is at its heart the process ##n\rightarrow p^+ +e^-## where a neutron, which is usually inside a nucleus but could be free, turns into a proton and an electron. I would not use the term "break" for the neutron since that would imply the neutron is made up of a proton and an electron, but it is not. This ejection of the electron has nothing to do with ionizing an atom. Ionizing an atom is when you take an already existing electron from the atom's shell of electrons and remove it. In a beta decay, the electron comes from inside the nucleus, not from the shell of electrons which swarm the atom.

    "Ionizing radiation" versus "non-ionizing radiation" is not an extremely clear-cut distinction. It is similar to like "harmful radiation" versus "not-harmful radiation". It really depends on the energy of the decay products.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook