Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

What does He-Like or Ni-Like mean?

  1. Feb 11, 2010 #1
    Hi all,

    Just wondering what does this mean, I understand it is related to a certain state of ionisation, but I would like to know why they are 'like' other atoms?


  2. jcsd
  3. Feb 11, 2010 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    Welcome to PF.

    He-like means the ion is stripped of all but 2 electrons. So it has a nucleus and 2 electrons, just like helium.

    Ni-like would mean an ion with the same number of electrons as a neutral nickel atom.
  4. Feb 11, 2010 #3
  5. Feb 12, 2010 #4
    thanks folks!

    The posts are conflicting though, if an ion (regardless of what it is) is stripped to a single electron, we can regard this as being H-like right? In this case does the nucleus remain the same?

    Bob S says that an un-ionised Ni atom can be regarded as He-like, because it has two outermost e's. This seems a bit fuzzy, since then there would be a lot more atoms that are He-like, hence rendering the comparison somewhat useless.
  6. Feb 12, 2010 #5


    User Avatar
    Science Advisor
    Gold Member

    The nucleus remains the same.
    Also, I would have thought that the word "He-like" would be reserved for an ion which not only has 2 electrons, but also that those electrons form a filled outer shell. I.e Ni would not be He like?
    This could of course only happens if the system is ionized to the point that only the 1s electrons remain and all other electrons in higher shells have been stripped away.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook