A possible set of quantum numbers for the last electron added to complete an atom of gallium (Ga) in its ground state is
A) A
B) B
C) C
D) D
E) E

Question

A possible set of quantum numbers for the last electron added to complete an atom of gallium (Ga) in its ground state is 
A) A 
B) B 
C) C 
D) D 
E) E

Quizplus · Accepted Answer

The last electron added to complete an atom of gallium (Ga) will occupy the lowest energy orbital available, which in this case is the 4p orbital. Therefore, the principal quantum number (n) is 4. The azimuthal quantum number (l) for the 4p orbital is 1. The magnetic quantum number (m) can have values ranging from -l to +l, so for the 4p orbital it can be -1, 0, or 1. The spin quantum number (s) can be either +1/2 or -1/2. Therefore, a possible set of quantum numbers for the last electron added to complete an atom of Ga in its ground state is 4, 1, 0, -1/2. This corresponds to the choice C.

A Possible Set of Quantum Numbers for the Last Electron