Question

The correct electronic configuration of Tc (Z = 43) is:

• A. \( [Kr]4d^6 5s^1 5p^0 \)
• B. \( [Kr]4d^3 5s^1 5p^3 \)
• C. \( [Kr]4d^5 5s^2 5p^0 \)
• D. \( [Kr]4d^7 5s^0 5p^0 \)
• E. \( [Kr]4d^5 5s^2 5p^1 \)

Hint:

Remember that the electronic configuration follows the Aufbau principle, which means orbitals are filled in increasing order of energy. The \( 4d \) orbital fills before the \( 5p \) orbital for elements with atomic numbers between 37 and 46.

Answer 1

The Correct Option is C

To determine the correct electronic configuration of Technetium (Tc) with atomic number 43, we need to fill in the electron orbitals according to the Aufbau principle.
1. The electron configuration of the noble gas preceding Tc is Krypton (\( [Kr] \)), which has the configuration \( [Kr] \) for the first 36 electrons.
2. Tc has 43 electrons in total, so after \( [Kr] \), we place the remaining 7 electrons:
- The 37th electron goes into the \( 5s \) orbital (since \( 5s \) is filled before \( 4d \)),
- The remaining 6 electrons go into the \( 4d \) orbital.
Therefore, the correct configuration is \( [Kr]4d^5 5s^2 5p^0 \), where the 5th and 6th electrons are in the \( 4d \) orbital and the 7th is in the \( 5s \) orbital.
Thus, the correct answer is: \[ \boxed{[Kr]4d^5 5s^2 5p^0} \]