Question

Which of the following is correct representation of electronic configuration of valence shell of N-atom in its ground state:

• A. 1 1 1
• B. レ レ レ
• C. Both (1) and (2)
• D. None of the above

Answer 1

Answer: (C)

Option (3)

Answer 2

Nitrogen (N) has atomic number 7, so its ground state electronic configuration is $1s^2 2s^2 2p^3$. The valence shell is the second shell, $2s^2 2p^3$. The $2s$ orbital contains two electrons with opposite spins (Pauli's principle). The three $2p$ orbitals are degenerate and contain three electrons. According to Hund's rule, these three electrons occupy each $2p$ orbital singly with parallel spins. Both options (1) and (2) correctly represent this configuration, differing only in the arbitrary direction of spins (e.g., all up vs. all down for parallel spins, or $\uparrow\downarrow$ vs $\downarrow\uparrow$ for paired spins).