20. Friday, Oct. 23, 2009

Electron spin, Pauli Exclusion Principle, Electronic configurations af atoms
1. Read chapter 6 (291-295) and chapter 7 (305-314)
2.  OWLs due Sunday

Major technical difficulties today.  We covered the lecture material with a combination of chalk, document camera, and one slide of PPT…

21 thoughts on “20. Friday, Oct. 23, 2009

  1. chem111-mjknapp Post author

    Hi Guillame,
    totally arbitrary! Kinda like defining “up” when you are in outer space, the ms value for an electron is only important when a magnetic field is turned on, as this is the only way to distinguish +1/2 from -1/2.

  2. chem111-mjknapp Post author

    Hi Brittany,
    no need to memorize that stuff. You need to know that light of a certain wavelength is produced when a transition between two energy levels occurs, such that DeltaE = hc/lambda

  3. Guillaume Pagnier

    @Alyssa
    ml depends on the “letter”. For example the letter in 3p is obviously p. Each letter has a sort of numerical value “l” that we just sort of need to memorize:

    s=0
    p=1
    d=2
    f=3

    To find ml we take the corresponding number “l” of p and see all the different possibilities it could be between -z and z. For p ml can be either -1,0,or 1. For quantum numbers with d it would be -2,-1,0,1,2. For quantum numbers with f the possible ml values are -3,-2,-1,0,1,2,3 and for quantum numbers s ml has to be 0 since there’s no such thing as a -0.

    Hope this helps

  4. Guillaume Pagnier

    Does anyone know if the first electron to go into an orbital always faces up/has a spin of +1/2?

  5. Alyssa Tyas

    can someone explain the ml thing.. like in OWLS 7.1b. 3d has 5 possibilities for ml.. but 3p only has 3.. I havn’t read that yet but the owl feedback just says ml=-1,0,or 1

  6. Brittany Bausch

    Hello Professor,
    I am re-reading the assigned pages in the book and I was wondering if we need to know specifically what n level will create what color light. For example on page 280 example 6.3 the question is asking what is the wavelength of the green line in the visible spectrum of an excited H atom. Should we know that n=4 to n=2 will produce a green light? I understand n>2 to n=2 will produce a visible light should i memorize all the colors produced at specific n stages?

    Thanks again,
    Brittany Bausch

  7. Brittany Bausch

    Hello Professor,
    I was wondering if you have any advice on what questions in the book we should try in preparation for our second exam.
    Thank you,
    Brittany Bausch

  8. Derek Melzar

    Tim, Prof. Knapp has said many, many times that although there are due dates, he’ll always accept them if you do them w/in the 24-HOUR GRACE PERIOD! Even, though you’ll get a check-minus for now, he’ll go back and fix it later; hope this helps.

    Cheers, Derek.

  9. Tim Groves

    Professor Knapp,

    Is there a lay over period with Lab Owls? Can the 10/23 lab owls be done today for instance and still receive credit?

  10. Laura Houde

    Chis,
    My guess is yes because we will still be doing calculations such as conversions and what not.

  11. Brithny

    @chris
    my guess is that we should bring a calculator for the second exam. We probably are going to have problems that would involve a calculator (eg. calculate the energy of an electron).

  12. chem111-mjknapp Post author

    Derek,
    necessary equations will be provided. But the really issue is that each student needs to know how/when to use them.

  13. Derek Melzar

    Professor Knapp,

    Will you be providing us with EVERY single equation we will need for exam 2, or will we be required to memorize any? Thank you.

    Cheers, Derek Melzar

  14. Taylor Estupinan

    Jesse,
    N is the principle quantum number and specifies the energy and average distance from the nucleus. L is the azimuthal quantum number and specifies the sub shell and the shape. And M is the magnetic quantum number and specifies the orbital orientation.

    L= N-1 to zero
    M= L to -L

    Let’s say that n=4
    Then L would be (4-1)= 3
    So L would range from 3 to 0… 3, 2, 1, 0

    M= L to -L
    So if L is 3 then M would range from 3 to -3 including 3, 2, 1, 0, -1, -2, -3

    The total number of orbitals is N squared. So since N=4 then the number of orbitals would be 16.

  15. chem111-mjknapp Post author

    Taylor:
    Exam 2 will cover all material from the end of exam 1 through the day just before Exam 2.

  16. Taylor Estupinan

    I saw on someone else’s post that chapter 3.9 will be on exam 2. Will exam 2 be everything from the beginning of the year until now? Or what chapters exactly should we specifically study for the exam?

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