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Homework Help: Help me out with electron configuration. :[

  1. Jan 16, 2008 #1
    1. The problem statement, all variables and given/known data
    What is the atomic number if the electron config is 1s2, 2s2, 2p6, 3s2, 3p4.

    2. Relevant equations
    How do I solve for electron configurations using a periodic table?

    3. The attempt at a solution
    I don't really have any, I am studying for a mid-term and this is all stuff I barely understood in the beginning of the year, and... well... Time makes fools of us all.

    I'm not asking for a direct answer, in fact, I don't want that. I want to figure out what I'm missing (in terms of information) on how to tell the electron configuration based on either the electron configuration itself --> element or vice-versa.

    Any help is very much appreciated. :)
    Last edited: Jan 16, 2008
  2. jcsd
  3. Jan 16, 2008 #2

    what does 1 tell you? Think orbitals.

    What does s tell you? Where would you find the s group?

    what does 2 tell you? Think electrons, but which electrons?
  4. Jan 16, 2008 #3
    I know as far as to say that 1 is the energy level, s would be the sub-shell (spdf, 1357) and the ^2 would be the number of electrons within the sub shell.

    But regardless, I don't know how to use that information and look at a periodic table and say, "That is..."
  5. Jan 16, 2008 #4
    ^2 would be the number of electrons within the sub shell.
    Exactly, so consider what info the atomic number gives in terms of electrons.

    Lithium has an atomic number of 3, its config is 1s2 2s1, do you see the relationship?
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