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### Fourth Quantum Number

Posted: Wed Apr 25, 2018 9:40 pm
Do we always need to calculate the fourth quantum number or do we only need to specify it if specifically asked?

### Re: Fourth Quantum Number

Posted: Thu Apr 26, 2018 11:33 am
I think if the question specifically asks, but its pretty staight forward; it's just asking if the electron spin is up or down.

### Re: Fourth Quantum Number

Posted: Thu Apr 26, 2018 2:09 pm
The fourth quantum number is used to indicate the orientation of the two electrons in each orbital. The values for ms are +1/2 and -1/2. An atom is the most stable when its electrons have the lowest possible energy.

I think that you will be able to determine what the fourth quantum number is based off of the other quantum numbers.

### Re: Fourth Quantum Number

Posted: Thu Apr 26, 2018 11:08 pm
I am confused on how we would determine if an electron is spinning up or down?

### Re: Fourth Quantum Number

Posted: Sun Apr 29, 2018 2:03 pm
I don't think you necessarily need to calculate whether the spin is up or down, you just need to know that if there are 2 electrons occupying the same orbital, one will spin up and one down.

### Re: Fourth Quantum Number

Posted: Sun Apr 29, 2018 5:02 pm
I'm not sure if we actually need to calculate whether the electron is spinning up or down but if you're given the ms value of +1/2 you should know that it means the electron is spinning up and if you're given the ms value -1/2 you should know that the electron is spinning down.