Question

How many electrons in a cesium atom can have the quantum numbers of n = 3 and ml = -2

Answer 1

CESIUM CONFIGURATION

1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s1

N = 3 meaning third orbit

M = -1 means P orbit or B orbit

SO THERE ARE TWO ELECTRONS WITH M = -1 IN P ORBIT AND TWO ELECTRONS WITH M = -1 IN D ORBIT

Answer 2

"n" represent the 3 energy level
"ml" represent the orbital

cesium atom configuration: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s1
since the n is 3, it presents the third energy level, we are talking about the 3s2 3p6 and 3d10 of the configuration

remember that each subshell has a specific number of orbital, and each orbital can hold 2 electrons.

s= 1
p= 3
d= 5
f= 7

a good way to remember the ml quantum number is to think of them as in a ruler with respect to the number of the orbitals. like this:

s (1)= 0
p (3) = -1, 0, +1
d (5) = -2, -1, 0, +1, +2
f (7) = -3, -2, -1, 0, +1, +2, +3

as you can see, only the "d" and "f" subshell have the ml "-2". but according to our electron configuration, we only have 6d10 not "6f". so we only have one orbital having -2, which mean 2 electrons (since there are two electrons per orbital)