The correct set of quantum numbers for the valence electron of an element in the 3rd period & belonging to the Alkali metals is
Correct answer: D. N=3. L=0. M=0. S=+½
- A. N= 2. L=0. M=0. S=+1/2
- B. N= 3. L=1. M=0. S=+1/2
- C. N= 4. L=0. M=0. S=-1/2
- D. N=3. L=0. M=0. S=+½
Explanation
The correct set of quantum numbers for the valence electron of an alkali metal in the 3rd period is N=3, L=0, M=0, S=+½, indicating a 3s orbital. Alkali metals in the 3rd period, like sodium, have their outermost or valence electron in the 3s orbital. Option A is incorrect because it corresponds to the 2s orbital of the 2nd period. Option B is incorrect because it describes a p orbital, not typical for alkali metals' valence electrons. Option C is incorrect because it refers to the 4s orbital of the 4th period.
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Quantum numbers describe an electron's energy level, subshell, orbital orientation and spin. You examine the principal, azimuthal, magnetic and spin quantum numbers, their allowed values, orbital capacity and how they determine electronic configurations and distinguish electrons within an atom.
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