Question

multiple choice 1 point
what is the predicted noble gas configuration of rhodium (rh)?
kr5s²5d⁷
kr4d⁸5s¹
xe5s²4d⁷
kr5s²4d⁷

Explanation:

Step1: Determine the noble gas core

Rhodium (Rh) has an atomic number of 45. The noble gas with an atomic number less than 45 is Krypton (Kr) which has an atomic number of 36. So the noble - gas core is [Kr].

Step2: Fill the remaining electrons

We have \(45 - 36=9\) electrons to fill. According to the Aufbau principle and electron - filling rules (with some exceptions for d - block elements), for elements in the 4d series:
The general form of electron configuration is \(ns^{2}(n - 1)d^{x}\). But for Rh, due to the stability of half - filled and full - filled sub - shells, the electron configuration is \([Kr]4d^{8}5s^{1}\) (a single electron in the 5s orbital and 8 electrons in the 4d orbital). Let's check other options:

• Option \([Kr]5s^{2}5d^{7}\): The d - orbital should be \(4d\) (not \(5d\)) for the 4d series elements.
• Option \([Xe]5s^{2}4d^{7}\): Xe has an atomic number of 54, which is greater than 45.
• Option \([Kr]5s^{2}4d^{7}\): Having two electrons in the 5s orbital and 7 electrons in the 4d orbital does not follow the electron - filling preference for Rh (to have a more stable configuration with one electron in the 5s and 8 in the 4d).

Answer:

\([Kr]4d^{8}5s^{1}\) (the second option)