Identify the 4 quantum numbers of the highest energy electron in an atom of bromine

Question

Please explain how to do this in detail, thanks!

Answer 1

Quantum numbers

n is the principal q.n. and starts at 1 ...

l is the azimuthal q.n. and starts at n minus 1 so 0 ...

ml is the magnetic q.n. and ranges from -l to +l

ms is the spin q.n. and can be either -1/2 or +1/2

So, let's start with n = 1

then l can only be 0

and ml can only be 0

but ms can still be either -1/2 or +1/2

Thus, one electron will have the set of q.n.

n = 1, l = 0, ml = 0, ms = -1/2

This is an electron in the 1s orbital with negative spin

And another electron will have the set of q.n.

n = 1, l = 0, ml = 0, ms = +1/2

This is the other electron in the 1s orbital with positive spin

Notice that the "1" comes from n, the principal q.n.

and that the s orbital comes from l, the azimuthal q.n.

The opposite spinning electrons can pair

So, the "highest energy electron" for He with the electron configuration 1s² can be either set of q.n.

For Br, start with the electron configuration for the 35 electrons

can write the complete or condense versions, either way you'll see the "highest energy electron" ...

n = __________

l = __________

ml = __________ bit of a trick question for this q.n. any of the three are ok

ms = __________

Provide a comment if you need a bit more guidance.