Consider ground-state helium having two electrons in orbit.If one of the electrons has quantum numbers (n,ℓl,m₁,m_s)of 1,0,0,-1/2 respectively,the quantum numbers for the other electron will be A)1,1,0,-1/2. B)1,0,0,+1/2. C)1,1,1,+1/2. D)none of the given answers.

Question

Quizplus · Accepted Answer

The first electron has quantum numbers n=1, l=0, ml=0, and ms=-1/2.
Since the two electrons in the ground state of helium have opposite spin, the second electron must have ms=+1/2.
By the Pauli Exclusion Principle, no two electrons in an atom can have the same set of four quantum numbers. This means that the second electron cannot have the same quantum numbers as the first electron, except for ms.
The only choice that has a different set of quantum numbers than the first electron, except for ms, is B with quantum numbers n=1, l=0, and ml=0.

Consider Ground-State Helium Having Two Electrons in Orbit