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Homework Help: Electron configuration for ions

  1. Apr 22, 2008 #1
    How would I write the configuration for ions? Would I alter the last subshell (e.g. 1s2 2s2 2p6 3s2 3p6 4s2 3d10: I change 3d10) or the shell with the n and l (1s2 2s2 2p6 3s2 3p6 4s2 3d10: I change 4s2)? Thanks.
  2. jcsd
  3. May 7, 2008 #2
    If your ion has a negative charge, add one electron to the electron configuration. If your ion is positive, subtract one electron.

    For example, take Na. The electron configuration for the atom is [Ne] 3s1. If you have Na- it becomes [Ne] 3s2 & Na+, just [Ne].
    Another example, suppose you have Cl, the electron configuration is [Ne] 3s2 3p5. Cl- is [Ar] & Cl+ is [Ne] 3s2 3p4. Notice how you add & subtract from the orbital with the highest energy

    You have to be careful with the transition metals. Take for example Ti, its electron configuration is [Ar] 4s2 3d2. Ti- is [Ar] 4s2 3d3. But here is where it "can" be tricky. Ti+ is [Ar] 4s1 3d2. The d orbitals are written after the s, but the 4s orbitals are still of higher energy. So you remove from them first, before the d orbitals.
  4. May 9, 2008 #3
    This tricky was on our test last week and....I totally lost lol.
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