Question

How many electrons in an atom could have these sets of quantum numbers?  

n=2 --> number electrons = ? 

n=5, l=2 --> number electrons= ? 

n=7, l=1, ml=-1 --> number electrons= ?

Answer 1

Part (a)

Eighteen electrons can have the designation n = 3.

There is 3s, 3p, and 3d orbitals. The s orbital can hold 2 electrons. The p orbital can hold 6 electrons and the d orbital can hold 10 electrons. Summing these values we get 2 + 6 + 10 = 18 electrons.

Part (b)

Ten electrons can have the designation n = 5 and l = 2.

n = 5 and l = 2 is 5d. The d orbital can hold a maximum of 10 electrons.

Part (c)

Two electrons are in n = 6, l = 3 and ml = -1.

Only 2 electrons are allowed in each suborbital, which is what ml is.