Question

The number of \(f\) electrons in the ground state electronic configuration of Np (\(Z = 93\)) is _________. (Integer answer)

Hint:

Memorize the specific electronic configurations of early actinides (Th to Np) as they often deviate from regular patterns (e.g., presence or absence of \(6d\) electrons).

Answer 1

Correct Answer: 4

Step 1: Understanding the Concept:
The electronic configuration of actinides (\(5f\) series) follows the filling of \(5f\), \(6d\), and \(7s\) orbitals.
Step 2: Detailed Explanation:
Neptunium (\(Np\)) has atomic number \(Z = 93\).
The noble gas core is Radon (\(Rn\), \(Z = 86\)).
The ground state electronic configuration is:
\[ [Rn] \, 5f^4 \, 6d^1 \, 7s^2 \]
Counting the electrons in the \(f\) subshell:
The number of \(5f\) electrons is 4.
Step 3: Final Answer:
The number of \(f\) electrons is 4.