The electron configuration 1s2 2s2 2p6 3s2 3p6 4s2 3d12 4p6
A) is valid and represents the ground state of an atom
B) is not valid becuase it violates the Pauli principle
C) is valid and represents an excited state of an atom
The correct answer and explanation is :
The correct answer is C) is valid and represents an excited state of an atom.
Explanation:
The given electron configuration is:
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹² 4p⁶
This configuration appears to be that of an atom with electrons distributed into different orbitals. Let’s break it down:
- 1s² 2s² 2p⁶ 3s² 3p⁶ 4s²: These orbitals follow the normal sequence of electron filling, where electrons fill the 1s, 2s, 2p, 3s, 3p, and 4s orbitals based on increasing energy levels and the Aufbau principle.
- 3d¹²: This is where the issue arises. The 3d orbital can hold a maximum of 10 electrons, but in this configuration, it is shown with 12 electrons, which is not possible in a single 3d orbital. This violates the maximum occupancy rule for the d orbitals. The 3d subshell can only accommodate 10 electrons in its available orbitals (5 orbitals, each with 2 electrons).
- 4p⁶: This configuration correctly fills the 4p orbital with 6 electrons, which is within the allowed limit.
Given this information, the configuration violates the rules of electron occupancy for the 3d subshell, which makes it invalid as a ground state configuration. However, it can represent an excited state. In excited states, electrons can occupy higher energy levels than they would in the ground state, and electrons may “jump” to higher orbitals, leading to unusual configurations like this one.
In summary:
- The electron configuration violates the Pauli exclusion principle (by having more than 10 electrons in the 3d subshell) and the Hund’s rule for ground-state configurations.
- The configuration is valid as an excited state, where electrons can be excited to higher energy levels beyond the typical ground-state configuration.