Question

e. what is wrong with the following electron configurations: 9. kr: 1s²2s²2p⁶3s²3p⁶3d¹⁰4p⁵ 10. 1s²2s²2p⁶3s²3p⁶3d¹⁰4s²4p⁶5s²:

Explanation:

Step1: Analyze electron - filling order for [Kr] configuration

The electron - filling order should follow the Aufbau principle, Pauli exclusion principle, and Hund's rule. The noble - gas core [Kr] represents 36 electrons. The configuration should start from the correct energy levels after the noble - gas core. The given configuration has incorrect orbital notations and incorrect filling order.

Step2: Analyze second configuration

In the configuration $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}3d^{10}4s^{2}4p^{6}5s^{2}$, the problem is that the 4s orbital should be filled before the 3d orbital according to the Aufbau principle. The correct order of filling for electrons after $3p^{6}$ is $4s$ first, then $3d$, then $4p$. So the correct configuration for a neutral atom with this number of electrons should have the $4s$ orbital filled before populating the $3d$ orbitals.

Answer:

1. Incorrect orbital notations and filling order.
2. 4s orbital should be filled before 3d according to Aufbau principle.