Answer to Question #68887 in Physical Chemistry for a

Question

Whats 31th electron of As Quantum Numbers?
actually this is my question : which one is filled earlier? ml=-1 or ml=+1
please mention to reference of your answer.
tnx

Answer 1

Gallium, Ga, is located in period 4, group 13 of the periodic table and has an atomic number equal to 31. This means that a neutral gallium atom will have a total of 31electrons surrounding its nucleus.
So, the highest-energy electron found in gallium is located in a 4p-orbital, which means that right from the start you know that the value of its principal quantum number, n, will be 4.
Now for the angular momentum quantum number, l, which describes the subshell in which the electron resides.
Notice that the fourth energy level has total of 4 subshells, each corresponding to a different value of l
• l=0→ the s-subhell
• l=1→ the p-subshell
• l=2→ the d-subshell
• l=3→ the f-subshell
SInce your electron is located in the p-subshell, it follows that its l value wil be 1.
The magnetic quantum number, ml, tells you exactly in which orbital you can expect to find the electron.
For the p-subshell, l=1, the magnetic quantum number can take the values
• ml=−1→ the px orbital
• ml=−0→ the py orbital
• ml=−1→ the pz orbital
Since the p-subshell only contains one electron, you can place it in the first available p-orbital, which is px, for which ml=−1.
Finally, the spin quantum number, ms, can only take one of two possible values
• ms=−12→ a spin-down electron
• ms=+12→ a spin-up electron
Since the orbital only contains one electron, it follows that it could be either spin-up or spin-down, so you get two possible sets of quantum numbers
n=4→l=1→m;=−1→m2=−12
A spin-down electron located in the 4px orbital
n=4→l=1→m;=−1→m2=+12
A spin-up electron located in the 4px orbital