ST. LOUIS -- When the Boston Red Sox signed Mike Napoli this past winter, there were a number of possible outcomes. He could hit a little, the way he had in 2012, putting up an OPS+ of 113. He could hit a lot, like he had in 2011, with a 173 OPS+ and 30 home runs. Most likely, he'd fall somewhere in between.
The fourth quantum number is the spin quantum number, s. There are only two values for s, +Â½ and -Â½. These are also referred to as 'spin up' and 'spin down'. This number is used to explain behavior of individual electrons as if they were spinning in a clockwise or counterclockwise.
It is called the magnetic quantum number and it's sometimes symbolized by ml. No matter how many times you try to rotate a sphere, you will always end up with only one orientation. This means that there is only one magnetic quantum number possible for all the s orbitals. That is ml = 0. The p orbitals can have three different orientations, so they're assigned three different magnetic quantum numbers for the possible positions of the p orbitals - we have ml = -1, ml = 0, and ml = +1. The -1 means that the dumbbells are aligned along the x-axis, the 0 indicates that the dumbbells are aligned along the z-axis, and the +1 indicates that the dumbbells are aligned along the y-axis.