Question

What is the quantum number set of the ground-state electron that is found in lithium (Li) but not in helium (He)?

Answer 1

The quantum number set of the ground-state electron in lithium that is not found in helium is {2, 0, 0, +1/2}.

Step-by-step explanation:

In the ground state electron configuration of lithium (Li), the first two electrons fill the 1s orbital, which have the same set of quantum numbers as the two electrons in helium (He). The remaining electron in lithium must occupy the orbital of the next lowest energy, which is the 2s orbital. Therefore, the quantum number set of the ground-state electron in lithium that is not found in helium is {2, 0, 0, +1/2}.

Answer 2

The electron configuration of lithium atom is:
`Li:[He]2s^1`

The number "2" is the value of the principal quantum number "n". Letter "s" is associated with the value of secondary quantum number "l" and it is equal to zero. The value of "m" (or magnetic quantum number) is zero too. The quantum number set for the highest energy electron will be (2, 0, 0, 1/2).