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spin of a electron

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I have to know the spin of a electron and what I have in my notes has me confused.

1. If the # of neutrons and # protons of a element are odd the element has a whole spin # (1, 2, 3)

examples given:

2 H
11 B
14 N
17 O
33 S
35 Cl

(I think those are mass numbers not atomic #'s)

for the oxygen and sulfur I'm confused since I know that the number of protons is the atomic number which cannot be changed even if it is a isotope but for oxygen the atomic # is 8 and that is NOT a odd number and for sulfur the atomic # is 16 which would make the protons it has 16 so how is that odd?

basically:

B=> given mass: 11
atomic # :5
number of neutrons => 11-5= 6 (not a odd number)

Cl=> given mass: 35
atomic #= 17
number of neutrons => 35-17= 18 (again not odd)

I do not understand what they mean or is there a typo??

  • spin of a electron -

    I think they mean the nuclear spin here.

  • spin of a electron -

    But even if it is the nuclear spin I don't understand how the protons and neutrons #'s are odd when they are clearly even.

  • spin of a electron -

    Figuring the spin of an electron is really quite simple. In your notes, I believe you're confusing finding the number of neutrons with the spin.

    The spin is either +1/2 or -1/2. You can think of this as clockwise and counterclockwise.

    The periodic table is broken up into four sections. The two groups on the left, the ones in the middle, the six groups on the right, and the ones below.

    For any given section, the elements in the left half have a spin of +1/2. Those in the right half have a spin of -1/2.

    For example, in the S block (the two groups on the left)... H, Li, Na, K, Rb, Cs, and Fr all have a spin of +1/2. On the other hand, He, Be, Mg, Ca, Sr, Ba, and Ra all have a spin of -1/2.

    You can apply this to the other sections, too... the Boron group, the Carbon group, and the Nitrogen group all have a spin of +1/2 because they're on the left. The Oxygen group, the halogens (Fluorine group), and the noble gases (Neon group) all have a spin of -1/2.

  • spin of a electron -

    Actually I'm doing organic chemistry and according to a ppt slide C 12 has no spin and O 16 has none either.

    I'm basically looking at whether or not they will have a reading in NMR.

    The reason the oxygen has a spin in this case is because it's a isotope of O 16 and in this case is O 17.

    Can anyone who knows about nuclear spin help me out with this please.

  • spin of a electron -

    Oh, sorry about that. :)

  • spin of a electron -

    The spins of the protons neutrons will pair up antiparallel, so, they all cancel out unless there is an "odd one out". If you have an odd number of neutrons + protons, then the spin is
    hbar/2, otherwise it is zero.

  • spin of a electron -

    Okay then thanks Count Iblis

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