Question

Two of the three electrons in a lithium atom have quantum numbers of n = 1, l = 0, ml = 0, ms = +1/2 and n = 1, l = 0, ml = 0, ms = -1/2. What quantum numbers can the third electron have if the atom is in (a) its ground state and (b) its first excited state?

Answer 1

ans)

from above data that

we know that the

Here The maximum number of electrons that then = 1, l = 0 sub shell can contain is 2

The atom is in its ground state, it contains the

the third electron must go into the n= 2, l = 0 sub shell.

For this sub shell, the magnetic quantum number can only be zero (ml =0)

The electron can have a spin quantum number of either ml +1/2 or -1/2

The third electron can have one of two possibilities for the four quantum numbers

so the answer is

a) n =2, L = 0, ml = 0, ms = +1/2 and n = 2, L = 0, m L = 0, ms = -1/2

now we have to observe that the its first excited state?

Here When the third electron is in the first excited state, there are six possibilities for the four quantum numbers

1)

n = 2, L =1, m l = +1, ms = +1/2 n = 2, l =1, ml = +1 ms = -1/2

2)

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

3)

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

so this is information about the (a) its ground state and (b) its first excited state